Im sorry to hear about this =/ This is a situation that always sucks.
Honestly, there really isn't an easy answer here (Although, if there was, I doubt you would be asking this here). Are they asking you to hand them over every piece of non-christian item you have, or at they just asking you to just tell them that you follow God? The other question is are you willing to bend the truth to make it work for you? I know this seems underhanded, but unless you are able to sit down and talk with your dad about this, one on one, or you just hide it when your family is around, I don't know much you can do.
Its possible, you may have to sacrifice one or the other, for a little while, but they are family, and should be able to make room for you, atleast if not now, a bit in the future.
I hope everything goes alright.