You don't need a gun to kill people.
The dying thoughts of a fallen solider:
Guns are loud and messy; there are far more elegant ways to kill a person. The doctor knows this, he can pretend to be a pacifist all he wants, but he's a warrior. You'd better hope when he lands in the middle of a war, he lands on your side, because if he doesn't you've lost. You don't just lose your life, you lose everything you've ever fought for. History makes you the bad guy.
The doctor: the one who heals, who helps, who saves lives, if he lands on your side of the battlefield that is.