Can you give me a reason to believe in God? I sometimes think he's there and then other times...hes nowhere

i have had a rough life.my dad was abusive.DHS never did anything.finally at 16 he beat me so badly that the school found out and I had to go to the ER.I live with my mom now.they are getting divorced.she moved out because of the beatings but he got custody of us somehow at a court hearing November 2006. But when he beat me so badly last november i got an order of protection. They are still not divorced after 2 in a half years. my point is...i honestly think there is a demon in my father. I think he is possessed. no one knows why he is so abusive and controlling...if there is a god...that he would let me suffer so badly through all the trama ive been through if he was really there. Though again i think about it like " maybe this had to happen to me for my mother to get us back" . we went to court back in january and he was convicted of domestic ault on a minor. he got 2 days in jail and 11 23 probation.i personaly dont believe thats enough. but is that bad to think about ur own dad?