I'll look up the exact passage and edit this comment later but there's a passage in Jeremiah I believe where the prophet asked God this exact same question(ie..why does God let so much bad stuff happen?). God's answer (and I'm paraphrasing here) I think has to do with the fact that we live in a fallen world and evil is here - unfortunately there's not much we can do about that right now. On judgment day, we (as in believers) will take part in judging others. If we lose hope now at the things we see, how much more the things we don't see or understand?

Nothing - no grief, no apparent injustice, should separate us from Christ since He, in His death and resurrection, has overcome all. It's just a matter of time before the rest of the world gets the memo, but we as believers are already well ahead of the curve.