Understandable because of sin and evilness. Fine no ,and in the end everyone answers to a Holy God, because no one is getting away with anything.You have people who undergo terrible things and lose all faith in God. I've met people who were enslaved and tortured (yes: literally that. Ethiopian, 1990's) and watched their family and village killed in front of them. I think its easy to understand why you might lose your faith in a loving God when you live through that. I can't blame the person for rejecting God: it seems to me to be totally reasonable. Who is responsible there? Who is responsible when a child is raped and abused, and grows up mistrusting everything including religion? The child? No, that isn't right.
I guess what I'm saying is the world can be shockingly ugly and messy, and it perenially surprises me (it really shouldn't, but it does) how hard people work at insisting that it is somehow understandable and just fine. I mean, if your religion helps things make sense to you, fine. I really can't criticize. But isn't it reasonable to say that no amount of explanation can make some things make sense?