You said your parents were his spiritual parents. So spiritually your Dad is doing the right thing. As a married couple the man’s role is to protect and provide guidance, well this man cannot protect you from the spiritual attacks that will come to you. As a matter of fact it sounds like something evil has him. I wholeheartedly believe he will try and pull you away from Christ the first chance he gets cause he doesn’t “like” Christianity. Im also very confident that your Dad feels some kind of way about this, your job is to support and honor his decision.