Why Does God Allow Bad Things to Happen???

Okay why am I writing this as a blog??? Well honestly I don't really know why I am...but it has been a question that I have thought about for quite some time. But really why does God allow bad things to happen in the world??? Okay I know kinda why God allows us, as Christians, to go through tough times and that is to help us and to grow us and help us to become more like him more or less. But why does God allow bad things in the world to happen??? To me it seems like if God really truely did care then he wouldn't let things like that happen. But he does...why??? Is it casue he only cares about certain people and since he is God he all ready knows who will go to heaven or not??? I mean like will a the war and killing and all that junk why does God want it to happen??? Doesn't God care what happens to people??? It seems like he cares sometimes but then not other times??? Like with 9-11 there was a bunch of lives lost and if that other airplane and not been tried to be stopped then a whole bunch more people could have died...but God didn't let that happen, why??? Okay well maybe I'm jsut a confused little person but that's nothing new...I mean it seems to me if God really cared then he wouldn't let bad stuff happen...casue well when that happens that just makes you really doubt that there is a God...or at least for me it does. Okay I know that is probably wrong but it's true at least for me it is sometimes. And even when I face trying times in my own life...sometimes I wonder if God really does care...I mean sure he cares about some people I can see that but then other well it just seems like everything is crashing down in their lives. I know it and overwhelming and frustrating feeling...okay well that's all I have for now. So yeah my basic question was why does God allow bad things to happen? And also it seems like the wrong in the wrong (big or little) in life goes undectected and nothing ever happens. But it seems like if we do something everyone jumps on us for it. Okay that's jsut my thoughts going on in my little head for today...