My mother came out last year and said she'd been having an affair. She got full custody even though she knows I want to stay with my father and that I think it's a sin. She wont let me got bible study anymore because of it. I also don't like her girlfriend. She gets really aggressive when I oppose her beliefs.
I just want to be with my father. He's always been there more, even when I had my period.
People are saying some awfully ignorant things in this thread. Custody is different from visitation. That one parent was awarded custody, in most states means that the parents could not agree on joint custody. Therefore the implication that your dad did anything is likely wrong based on what you have said.
Different states have different laws, but one parent poisoning the child against the other parent is often enough to favor one parent if all other things are equal.
That said. If you want to live with your father, that is okay. While the court tries to act in the best interest of the child, they do not always get it right. But if the court decided, it is only because your parents could not.
If you are unhappy, feel free to vent. But this will not change anything. Speak with your parents about what you want. Do not get upset if you feel that they are not listening. If you feel yourself getting upset, calm down and try again later. Different states have different laws, so there is no way to know at what age your opinion will hold the most sway. And no way you should give the information required to know out over the internet.
The best advice I can give you is to ask a trusted adult i.e. a teacher to help you understand the law and your rights.
Custody is largely irrelevant. What is more relevant is visitation. What level of visitation do you have with your father?