I wouldn’t call it support or comfort but I often think if there was reincarnation then everyone must eventually live every life, so those who are killing will also be the killed, we will all end up living the lives of those we despise too, and that would be fair.
Also I think about just how little we can perceive of the world and universe, we have techniques and senses to see this pinhole view, and mostly trust it, but it’s so much bigger and more complex than we can imagine or perceive.