This is not my own work. This story was written by Anirban Chakrabarti and I specifically asked for and received permission from said user to post this. If you want to view the original comment, you can find it under a 30 minute loop of Children of the Omnissiah uploaded by a user going by the name of Orpheus.
You are approaching one of the great forges of Mars through the Martian wastes. Dust encompasses all the eye reaches, a desolate landscape of red in all its shades. Tall, gargantuan silhouettes rise up in the distance like the weathered bones of some incomprehensible beast, furnaces and blinking lights defining their forms through the Martian blizzards. The divine machine temples of Holy Mars streak smoke as they forge weapons for the Imperium's eternally hungry war machine. Even through the grating winds comes the ever present binary chant of the priests in red... here and there you see processions of Large vehicles carrying machines of arcane and unknown design. Flanking these slow progressions are the skitarii who waft incense and raise their arms up to the sky in praise of their Machine deity... they closely follow one of the machine priests of the Cult mechanicus. He/she/it, does not resemble you... that being is something beyond you. Wires trail behind its rich red robes and bionic arms hang over its stooping head. It looks at you... the red ocular implants glow and flicker, perhaps reading your very thoughts. The wire riddled breathing apparatus trailing misty breaths... if flesh at all remains within it, it is lost in the darkness of its hood. It makes the sign of a blessing towards you as you cross the procession and moves on.
The forge walls are impossibly tall and laser batteries, cannon turrets and surveillance equipment jut out of the palisades... hundreds of thousands of tech-priests, skitarii, slaves, serfs, servitors ( all of them united with the machine to such an extent as to not be very different) melt into an ocean of human bodies going to and fro in what seems a frenzy but is in actuality an efficient system. The chant is deafening now. The smell of sweet oils and pungent incense is overpowering even through your rebreather filtering the dead air of Holy Mars. And at the gargantuan gates of the forge stand 2 titans, protecting the God-forge of the deus ex machina. Even from here, they appear tremendous things, your mind barely able to absorb the perspective... it is maddening how small even these warlord class machines are to the smog wreathed forge behind them. The massive walls are lines with banners, sculptures of past heroes among the Omnissiah's faithful. How incomprehensibly large it all is... you must sit down and weep... your knees give out and you can do nought but BOW to this mountain of metal and soot. The Omnissiah's presence feels palpable... your mind joins the reverberating binary chant. Omnissiah protects.