You can't just say God doesn't exist because bad things happen. Otherwise, everything and everyone would literally be perfect. 9/11 was planned and performed by Islamic terrorists. When we die, we will see God. He will either condemn us to hell or grant us life in heaven.
God doesn't "sort out" people when they sin, he lets people find out about God and repent, whether it be word of mouth from another Christian to something as absurd as a youtube video. The devil does indeed exist, and he creates bad things to temp Christians to turn away from God.
Think about it: Would you like to live a life of sin and luxury on Earth for less than 100 years then suffer eternally? Or do whatever it takes to fight the good fight, worship God, repent, and be blessed when you die?
If youre not convinced yet read this: In Christianity God wants everyone to be nice and kind to each other, don't hate. Someone else's view is this: It's okay to be a rotten banana peel because why the heck not. But I dont have that sort of philosophy, non-Christians are, as I said before, mostly meanies and terrorists. They think no one will punish them. God will, they are just reluctant to accept that while they live.