"of how the Catholic world went from Jesus’ principle of "Love thy neighbor" and "Let he who is without sin cast the first stone" to a full blown religious wars and the Inquisition"
One of my favourite debates, but probably not the right place and time for it, to discuss it fully.
But maybe a little bit:
1.Jesus said some other things as well, besides loving everyone, like he is there to bring the sword and he is not there to abolish the law(old testament) but to fullfill it. So of course there is lots of room for interpretation, but nevertheless, this allowed for all the archaic and brutal parts of the law, the old testament, to be included.
2.catholicism became state religion in a empire on the decline, close to collapse.
"but all the foot soldiers have is the cognitive dissonance between their orders and their dogma"
And the foot soldiers of empires, almost always had as the highest dogma - to follow their orders, not to morally judge them. And since the catholic dogma has a lot of battle descriptions included - even the thinking soldiers can find justification, without great cognitive dissonance. But sure, the christian military priests in nazi germany on the frontlines and such, probably had to have a bigger cognitive dissonance from their holy book and their actions.