Common* christian theology posits that God is a perfect judge of law and fact, seeing as she has both infinite patience, infinite subjective time, and accurate knowledge of everyone’s points of view.

“Why does evil persist on Earth then” comes down to either said evil being necessary for some unseen purpose, said evil being irrelevant to God’s plans, or said evil being the consequence of some mortal privilege. Or some combination thereof.

There has been a lot of christian thought about why evil persists, and settling on an answer to it is essentially the base of all persistent ecumenical schisms. Other religions add even greater complexity, because once you examine perspectives off the abeahamic tree you quickly find that not even “Good” is consistently defined.

The moral and philosophical questions don’t get much easier if you remove God from the equation, or even if you adopt a nihilistic “only the momentary physical now matters” perspective.

If you don’t believe me, try coming up with an answer to “why is killing bad” that you can get agreement on. (Not just “is killing bad,” but an actual casual why.)