Q. I don’t understand how God could do bad things to me!
A. Actually I have a bit of difficulty with this type of assertion. I've watched people spend decades trying to answer a question that probably has no answer. In the process they've lost their health, career, relationships, spirituality, and a whole host of other things. That seems rather counter productive and is a loss in and of itself.
The Biblical story of Job posed a similar question. The answer seems to be that God didn't do it and suggests that one’s Higher Power doesn't always interfere in the everyday lives of human beings to prevent the effects of injury and loss.
How human beings can orchestrate the death of innocent people in the name of a cause be is religious, social, or political is beyond me. How can they? It's an absolute oxymoron, especially when the deed is done in the name of God, or Mohammad, or Allah, or Buddah. It makes no logical sense to hear someone assert, "I passionately believe in such and such and I'm going to hurt you because you don't believe as I do." Or, "I don't like what you did so I'm going to do something hurtful to you in return."
Yes, human beings probably do have a tendency to want to even up the score. History is abundantly clear, however, that in many cases little good comes from it to say nothing of the resources wasted in the process. I can only chalk it up to a brain dysfunction of some sort (such as in a sociopathic personality) or to some unhealed woundedness in the person's life that turned into an addiction for revenge (as perhaps in the case of Hitler).