Nicolae Carpathia is described as clever, cunning, and charismatic. However, being indwelt by Satan severely cramps his style, making him into a fairly ineffective opponent strategically. What if... Thanks to Child of Music and Dreams who challenged me to write a Left Behind epilogue that still results in a Yahwist victory.
The timeline deviates around "The Remnant". This gives us about 3 years before the Glorious Appearing.
Carpathia has a talk with an unnamed underling. Carpathia decides to call off the siege. Satan asks what the hell he's doing. Carpathia explains that it is the most rational thing to do. Satan reminds Carpathia who's boss, de-indwells him, and threatens him with withering. Carpathia's security detail shows up after seeing Carpathia being tossed around the room by nothing visible. Satan kills them quickly and messily.
Automated alarms trip and an actual Army contingent shows up to defend their boss. Satan manages to repel almost all the ordnance thrown at him, but is subdued, at great human cost after being shot in the chest with a LRAD and dogpiled. The siege is lifted, much to the Petrans' confusion.
Fast forward a week or so. Satan is in custody. Carpathia goes into surgery for a heart and lung transplant and ends up in a Davros-like life support chair. He uses the three frog-like spirits to keep up the pretense that he is healthy, keeping them somewhat loyal on pain of pain, but since they will not follow orders - one of them tries to resume the siege when he is brought in front of camera - Carpathia just has to splice videos of them, and communicate to the world like that.
In Petra there is ardent discussion on what to do to make sure that the prophecies do not derail. Stay put and trust in God? Turn terrorist in an attempt to provoke the Unity Army into resuming the siege or outright attacking? Leave?
The Unity Army corps of engineers clears out the Jerusalem neighborhood at the top of the Mount of Olives, cuts the mount itself into three north to south to prevent it from being east north to west and justifies all this by building two canals in the cuts.
The Tribulation Force members that are still in America are likewise uncertain as to what to do. The Unity Army is leaving them alone but under surveillance.
The Earth's ecosystem is devastated. Carpathia has to put nearly every able bodied human on Earth who will obey him to work doing environmental cleanup, and has to impose rationing. Rather than trying to starve the Christians out, he makes sure that some Christians enclaves receive double rations, as if by mistake. This causes a lot of suspicion between them and everyone else.
The various Christian enclaves call a meeting, which is hard to get to due to the deteriorated state of the world infrastructure, and the various leaders yell at each other about possible moles, spies and plants until a decision is made to pray together about it, at which point it becomes obvious that it's just Carpathia's dirty trick.
Carpathia's PR department pivots this by publicizing the meeting (of course it was being spied on, who needs to plant moles when you have superior SIGINT) and its resolution to keep things as they are, this causes Christians to be liked even less by the rest of the population. Carpathia fixes the "ration glitch" after a few weeks, and decrees that ration chits will be shared equally between "loyalists", "lukewarms", and Christian rebels because it's the only way to make things fair without setting up a massive bureaucracy.
A few cries of Communism are rebuffed with pointing out that this is what most countries had to do during WW2; Carpathia recycles British war posters, mottos etc. wholesale and asks people to keep a stiff upper lip. The news start showing devastated lands and seas as "Acts of God" again, trying to paint Yahweh as the enemy.
Two parallel briefings at each faction's high command. The Christians are in high spirits: they know that deliverance is coming soon regardless of what their enemy does, and hazard picking a date for it. The Unity Government are pessimistic - it's obvious that despite the environmental cleanup work, the damage to the planet is extensive enough that it's time to start considering culling the population to last a bit longer (and there's no permanent fix in sight). Too many species lost, too much poison in the sea and so on.
Satan has been listening in to the latter discussion from his containment system, and has a proposal - let the prophecy return to its rails, and then derail it again AFTER Jesus restores the Earth to verdancy but BEFORE the sheep-and-goats judgment. Carpathia mulls it over, and decides to start with let's have doomsday clocks in major cities and on TV, taken straight from Tsion's preaching. The Christians object that "nobody knows the hour" but agree that it's probably pretty accurate.
Dwindling resources force some terrible compromises - violent criminals "given mercy" by quick execution and organ harvesting rather than wasting food on them; nonviolent criminals to be given reclamation work in biohazard zones; euthanasia to be made accessible and pretty much encouraged for the people who can't work. Carpathia worries that he has become the dictator that the Christians always painted him as. Satan taunts him and proposes his plan again; Carpathia accuses him of wanting to lose.
An infiltration blitz by the Tribulation Force exposes Carpathia's decrepit state to the public. Satan demands that they free him before they return from the raid, but of course the TF members will not help Satan in any way shape or form! They refuse to believe that Satan is in containment, and figure that he's letting everyone believe that he is for his own nefarious ends. Carpathia owns being "unmasked" and appears on TV without proxies for the first time. He looks roughly like Davros or Snoke. Rather than blaming Satan, he blames having made sacrifices for the greater good.
Baal, Astaroth and Cankerworm are let go and told that they are welcome to make a living as impersonators, if they want, but they are to stay away from their master Satan or face destruction. Predictably, they try to free him, after voting two to one to not try and get help from Christians. Their plan is poorly executed and lands them in containment.
The doomsday clock is ticking inexorably. Although the long-term hopes of the planet are grim, the Unity Army manages to make some areas of Earth function almost as well as they did pre-Tribulation. Notably, by now the Eden fertilizer has leeched all the deep-soil nutrients, so most of Israel is abandoned; the only two places that remain are Jerusalem and Petra, held by the Jewish and Christian remnant respectively.
At the start of the final year, Carpathia issues a decree restoring freedom of religion, noting that he has proven himself to be better than any God through hard work and sharing of the people's suffering, and fears no competition. Some religious groups reemerge, leaving the Unity Government with less control over the world but more control of loyal areas. The first children born after the Rapture are starting to go to school; the first elementary school in the world reopens with great fanfare, relatively small numbers of enrollees, and a renewed feeling of hope. Unsurprisingly, children are (officially or not) treated as very precious, perhaps over-pampered, given extra rations and so on.
The Community Co-Op is busted as in the original timeline, with Chloe being caught and executed - since religious freedom has been mostly restored, the bust happens because the Co-Op is accused of hoarding food and other essentials. Chloe bravely manages to not divulge information about the secret warehouses that Christians have, and is publicly executed after having been granted peace by an angel. However, the angel's ministry is filmed and rebroadcast all over the world; Carpathia dares the Christians to say that the footage is faked - which they cannot do, since it isn't - and spins the story into indicating that God Himself is on the side the hoarders running what is exaggerated as one of the main reasons why there is a food shortage.
The Unity Army by now has mostly converted itself into a civil protection organization, tanks turned into tractors and ships into mobile desalination plants. "Witch hunts" targeting Christians and even people who look like stereotypical angels ensue as the exhasperated populace wants to bring folk justice to hoarders. This results in a spate of avoidable deaths. Christians are supernaturally protected in many cases, but Jews are not and people who happen to look stereotypically angelic aren't either. Eventually, a portion of the Unity Army has to be reactivated - to protect the accused hoarders in Petra and Jerusalem from lynch mobs! Carpathia, ever the man of peace, calls on the Christian leadership to prove their good intentions by offering amnesty to hoarders who share their stashes.
A quick discussion within Trib Force leadership shows that the vast majority of Co-Op assets can be given away to the needy, assuming that the End Times timeline has not been compromise; they quickly decide that it hasn't, and reach an agreement with the people in Jerusalem to share these resources if they officially break off from Global Community aid. Carpathia is furious publically, and condemns the agreement, but privately notes that it was expected and pulls out of Jerusalem. The two cities and the 100-mile long strip of land between them are fenced in and effectively treated as their own territory. Like Pontius Pilate, Carpathia publically announces that he washes his hand of the whole area. (Privately, he uses up the remaining stockpile of nuclear weapons to build an atomic minefield just outside the protected area).
There are six months left. Some smuggling takes place due to the fact that the strip touches a part of the Dead Sea, which is easily reachable by river. A small part of the Unity Army remilitarizes to guard the strip; seizing the reorganization, Carpathia reorganizes the Unity Army into a much smaller force dedicated to that task, and assigns the bulk of its former assets to the civilian land reclamation agency that has been de-facto runnng the show for years. He also publicly promises to disband even this small army in a year and a half. A brief online exchange between Tsion and a reclamation foreman can be summed up with "There is no year and a half left!" "Well whose fault is that?"
Extensive damage to forests and marine vegetation is starting to lower the oxygen concentration in the air; everything else can be fixed if there's time to fix it - flowers and bees are slowly returning, concentrating people in safe zones has allowed nature to grow over much of the world's urbanized landscape, gas shortage and a push towards solar panels has alleviated pollution - but the oxygen problem is dependent on slow-growth vegetation, and probably cannot be fixed. Thanks to the loss of biodiversity due to the Bowl Judgement, the best Unity Government prediction (which is kept classified) is that even if the End Times timeline is disrupted, humanity has maybe one chance in three of surviving the next century.
Chaim Rosenweig, who let's not forget is a botanist, has reached similar conclusions: he takes it to the rest of the Trib Force, noting that a raid to retrieve the official-but-classified predictions that he correctly surmises Carpathia has made, accompained with a media blitz online and on TV right after, would expose Carpathia as a fraud and cause many to convert before it's too late.
When the Unity Government gave up Jerusalem to its inhabitants, they would not or could not keep the canals operating, so the Mount of Olives is returning to its original configuration. Carpathia offers to rebuild the canals, and provide free water; the Tribulation Force correctly surmises that he wants to disrupt prophecy and throws a wrench in the negotiation after only a few days of work, thrown in for free by Carpathia to show good will, had started. In fact, the terrain movement caused by such causes the Mount of Olives to settle into something like its original configuration. Carpathia saw this eventuality coming, and the first thing the workers did was bury nuclear mines there, too.
Three month to go. For a show of optimism and for propaganda reasons, Carpathia has authorized a space mission, to reopen the International Space Station. In truth, he hopes to turn it into a more secure containment facility for Astaroth, Baal, Cankerworm and Satan. The mission is a partial success, in that the ISS is reopened, but Baal, the one demon that had been stuck in the unpressurized payload bay manages to escape. Since he can change his appearance at will, Carpathia has little hope of recapturing the former impersonator. Even so, the recovery of space capability allows new satellites to be launched, restoring video communications around the world.
The Tribulation Force are about to launch their caper to expose Carpathia's reclamation plan as a fraud, when Baal comes before them, telling them that if they do not free Satan, the End Times timeline will be disrupted and there will be no deliverance, just a slow decline for life on Earth. Of course, they do not believe him.
The caper is launched, and is successful, due to some supernatural intervention. The Trib Force's raid has the side effect of allowing Baal to turn off containment around the three other demons in a parallel attack that interwined with the main raid. Satan immediately indwells Carpathia again, leaving Baal to take his place and shape in containment.
The Trib Force's announcement that the reclamation plan was always doomed causes some conversions and many riots. Carpathia, indwelt by Satan again, goes on TV and calms the masses with supernatural influence, then makes a show of appearing to regenerate and walks out of his life support rig. Carpathia is shown with his old appearance, although he is still wearing an external pacemaker and ventricular assist pump since Satan could not regenerate his heart. He claims to have figured out how to tap Satan's power for humanity's ends - cut to Baal pretending to be a weakened Satan in the containment system - which will be used to help restore life to the planet until homeostasis is reached again.
Once back in the saddle, Satan does his best to put the End Times timeline back on track by re-occupying Jerusalem and putting Petra under close siege again. However, Carpathia had left specific instructions to his commanders in case a second indwelling occurred: they are to continue with the original plan and lie in their reports to Satan that things have been put back where they were. Satan has supernatural charisma, but it only works locally, and the Unity Army has had to decentralize to cope with the damaged planet they are trying to rebuild: most regional commanders continue following Carpathia's plan.
A proposal to reopen the nuclear power plants that have been obsoleted by solar panels to use as electrolysis devices to replenish oxygen is quickly approved by Carpathia's council; Satan, not understanding what this even is, simply takes credit for the work. The Tribulation force correctly determines this to be yet another attempt to derail prophecy, and manages to raid one of the power plants, shutting it down. Afterwards, there is question about whether they have become the bad guys - they did just disable an oxygen-generating machine after all. A few moments of prayer clear the matter.
With two weeks to go before the Glorious Appearing, a few plants have been converted despite setbacks and that one act of sabotage; it becomes obvious that the oxygen levels can be maintained for a long time before nuclear fuel becomes scarce, hopefully giving the ecosystem time to adapt. Satan takes credit for this on TV, but is starting to realize that his men are only following his orders when he is in direct contact with them. He does not dare unindwell Carpathia to ask him what's going on, though, because last thime he did, he ended up locked in a containment system.
The Glorious Appearing happens exactly on schedule. The problem is, of course, that there is no Unity Army sieging Petra; the fields around the walled city are wide open, with the rare plant growing there. The only evidence of a siege is a fence warning that if the fence is trespassed by people who do not have the Mark, anything from motion-detecting sentry guns to nuclear mines may go off (In fact, the sentry guns are somewhat glitchy and have let the Trib Force out on their raids as explained before, and the nuclear mines are designed to go off only upon Carpathia's death).
Jesus solves the problem by simply teleporting the Unity Army members who were supposed to be at the siege just outside Petra's gate. About a million people were sleeping in other time zones, or doing reclamation work, or patrolling, and all of a sudden they are in desert-camo fatigues, holding guns that they haven't touched in months, around a city that they had written off. Tsion goes onto the walls and accuses the Unity Army of violating their own unilateral cease-fire. One of the field commanders recognises what is going on, and issues an immediate order to put weapons down and walk out. Satan, still indwelling Carpathia, goes on radio and countermands the order. The people operating the satellite link shut it down and broadcast a counter-order to drop weapons and walk away from a library of prerecorded orders made by Carpathia before being re-indwelt. This prevents Satan from commanding his army unless he's there directly, so he gets in a jeep with Leone Fortunato and moves towards Petra.
There is a brief, and somewhat surreal, conversation between Tsion and the field commander in which Tsion again accuses the Unity Army of violating their own ceasefire, the field commander points out that they were teleported there and they are in fact dropping their weapons and leaving, and Tsion haranguing the commander for treachery and aggression. (Note that unlike in the original timeline, Buck is still alive at this stage).
As the supposed Unity Army troops walk away from Petra's wall, they are teleported back where they were. When this happens, some of them panic, and shoot in the air or even at the walls with their rifles. A particularly unlucky shot hits Buck, ensuring that he dies as scheduled. Moments later, the light of Jesus has covered the earth (the eastern hemisphere anyway) and He is slowly moving to Petra. All those in Petra who needed it are healed by His presence. By now, Satan is close enough to the army in Petra that he can use the jeep's radio directly, without depending on a relay; his supernatural command forces some of the reluctant soldiers to obey when he commands a charge, and that's all Jesus needs to explode them in a shower of blood. A few of the people who found themselves driving tanks in the back manage to drive off, simply because they were out of range, but they too are teleported next to the wall and exploded.
Jesus leads the believers into a magical sprint between Petra and Jerusalem as Satan, still driven by Leone Fortunato, retreats there; as in the original timeline, the two get stuck in the mud created by all the blood on the sand, and Leone has to get out and push. As in the original timeline, Jesus reaches Bozrah; however, the town has been mostly abandoned, the only Unity Government presence being a few people to operate and guard the solar panel plant that had been built there. Like in Petra, a number of Unity Army workers who used to be soldiers are teleported to the village and then immediately blown inside-out so that the Supper of the Great God can take place. A number of key Global Community systems such as nuclear plants and submarines recognize having been supernaturally unmanned by dead man's switch systems that are designed to safely shut everything down; by Carpathia's orders before being reindwelt, they trip otherwise.
The remaining Trib Force members find a Hummer and go on ahead as Jesus, still followed at a distance by believers from Petra, reaches the Valley of Megiddo and finds it empty; the canals to Jerusalem have been turned into a pipeline. Yet again, workers who used to be soldiers, and soldiers who were guarding other posts, are teleported where they were supposed to be. This time there are also a number of horses and, for the simple reason that quite a lot of Army horses were used for meat months ago, a number of horse skeletons.
While this happens, Rayford, Mac, and Abdullah chase after Nicolae and Leon in a Hummer, watching the tremendous carnage as the majority of the remaining Unity Army forces are killed at the Valley of Megiddo amidst the words of Jesus and the hailstones that fall at the seventh Bowl Judgment. Nicolae and Leon are traveling to Jerusalem in the Royal Humvee with Viv Ivins when this happens, during which Viv Ivins is killed by one of the massive hailstones. God turns the marshes of blood to ice, which soon melts and becomes a thick mire. As Satan and Leon try to flee to Jerusalem, all the people in Petra are given supernatural power to travel from there to Jerusalem by running at 70 miles per hour.
For the final time, when Jesus and Satan finally reach Jerusalem, Unity Army reservists and civil protection workers who used to be active-duty are teleported under the Temple Mount, some on horseback, most on top of a pile of equine bones. Satan gives this extremely confusd contingent the order to charge an equally confused contingent of Jew holdouts who were minding their own business in Jerusalem and are likewise teleported in a defensive position above the Temple Mount. The Unity troops are afflicted with a flesh-dissolving plague that afflicts both humans and horses. Satan tries to curse God, but the moment he tries, a global earthquake occurs that levels all the mountains, destroying the beauty of the Earth, and elevates Jerusalem. The seismic event is picked up by sensors all over the globe, putting what is still working of Global Community infrastructure into last-chance-contingency mode.
Satan, still followed by Leon who seems to be the only one still affected by the Devil's supernatural charisma, find two surviving horses - the terrain has been made hard to handle by wheeled vehicles by now, and neither of them know how to drive a tank - and head to the Mount of Olives. The instant Jesus steps foot on the mountain, it splits into a valley running east to west; the nuclear mines planted there early explode from being dislodged, and take out both the Unity Army reservists and the Jewish rebels. Jesus is left looking onto the two craters that are supposed to be the Valley of Jehosaphat for a few long moments, during which a series of seismic aftershocks shape the valley as it was supposed to be.
Jesus enter Jerusalem through the Golden Gate. Satan and Leon attempt to flee on horseback, but to no avail, as the Archangel Michael captures them. The few automated flak emplacements still operating have no effect on the Archangel. Satan, Fortunato, and the three spirits are brought in front of Jesus for judgement. The three spirits humble themselves, but are destroyed. Leon bows before Jesus, but is sentenced to the Lake of Fire.
Carpathia does not bow, but his body fails him when Jesus casts Satan out of him, so he does end up bowing. Free again, Carpathia quotes Stalin to Jesus - "Kill one man, and you are a murderer; kill a million, and you are a general; kill them all, and you are God." Michael demands that Carpathia confess that Jesus is the Christ, which Carpathia readily does, adding that might doesn't make right and being a god doesn't make you good.
Jesus harangues Carpathia about allying with Satan and squandering his gifts. Carpathia answers that Jesus got it exactly wrong, and that he wanted to free humanity of both Yahweh and Satan. He then accuses Satan of having worked for Yahweh the entire time, as is written in the book of Job. Jesus ignores him, and demands that Carpathia confess that his life was a waste. Carpathia answers "Make me" and turns off his pacemaker, but right he dies, Jesus makes him by moving his mouth and tongue, and then throws him and Leon into the lake of fire. Jesus also deals with Satan, having Michael tie him up in a chain and also throwing him into the lake of fire.
The contingency systems that are left working - most of the land systems are gone after the global earthquake, but the seaborne systems largely survived - detect Carpathia's pacemaker having been turned off. Nuclear submarines which have been largely left unmanned by the Unity Army teleport respond to their dead man's handles and prepare to perform their scheduled resurfacing to receive radio orders; most of them respond correctly. All the remaining nuclear mines go off, finally destroying Petra and cutting a corridor of destruction between that city and Jerusalem, which ends up being surrounded by a ring of radioactive craters.
When the gathering has ended, the Trib Force members end up having dinner in Jerusalem as per the original timeline. All around them, the sky is scorched by radioactive clouds and ion storms.
On the day following the Lord's return, all the people of the earth, including believers, are gathered at the new Valley of Jehosaphat for the "sheep and goats" judgement by Jesus himself. Around the world, the submarines have emerged, and with the Unity Government systems having gone into contingency mode, receive no radio orders. Those submarines that had been set up properly by the vanished crew recognize this as an attack having succeeded, and prepare for automated second-strike launch. Approximately fifteen percent fail to do so.
All the believers who were considered the "sheep" Jesus had granted them to enter into His kingdom for caring for "the least of His brethren", and all the others that were the "goats", that didn't care for "the least of His brethren", Jesus does not give their day in court to the nonbelievers who had sacrificed much in the last few years in order to provide material and emotional support to their fellow humans, and sends every last one of them into everlasting punishment. Everything is quiet save for the hastily set up megaphones by some Unity Army relief workers, who used their last day on Earth to build a tape loop that denounces Jesus for cheating and lists the many instances of nonbelievers having made and kept vows of hospitality, clothed the naked, fed the hungry, and so on.
Amongst the throng of believers are the children of the Tribulation, those who grew up during the last seven years. The oldest are old enough to understand the last message of a dead civilization. The memories of their parents turned inside-out or swallowed by the earth are fresh and traumatic, and mix with the simple account delivered by damned men's voices. They listen. They learn. They will never forget.
After this, Jesus rewarded the Old Testament saints for their faith, and then rewarded the Tribulation martyrs for their faithful witness. When this was done, Rayford is happily reunited with his wife Irene and his son Raymie, now fully grown and having been deprived of his formative years, as well as with his friends and family members that went on to be with Jesus ahead of him. Buck (now going by his first name Cameron, since there isn't anything left to buck) and Chloe re-unite with Kenny, Tsion and Chaim are re-united as well as Abdullah and his wife Yasmine. The ICBMs launch. Rayford amusingly tells Irene that she is entitled to "one cosmic I-told-you-so" before they are all re-united with the rest of the resurrected members of the Tribulation force. Roll credits.
A post-credit scene shows the ICBMs completing the ascending half of their ballistic arc and converging onto Jerusalem, just as the ice canopy that will surround the world during the Millennial Kingdom starts to form.