Ok, I'm going to burst the bubble here - whilst you live in their house then their rules kinda supersede yours, I'm afraid. They are probably trying to do what they think is right, although listening to certain types of music does not necessarily cause Atheism any more than it would another type of belief/absence of belief. Ultimately, your religion or lack of it is your personal choice and they ought to respect that but at the same time, whilst you live under their roof you need to respect that in their home they may not wish to have certain influences around and they may be concerned how those influences are affecting you as a person, religious choices aside.
Have you even tried talking to your parents about your personal choices? Talking, not yelling or rebelling or trying to make things 100 times worse. A lot of parental reaction like this is the product of ignorance rather than wanting to anger or hurt their kids. If they are in the God squad they will feel a certain amount of responsibility for your spiritual state and might be finding it hard to let go and let you make your own choices about what you believe in/listen to/watch etc - this is something they'll have to learn to do, so give them a break. It's not easy if you think you've failed to raise your child the way you believe they ought to be raised. By attempting to eradicate certain perceived influences, it could be their way of trying to regain some control over the situation and trying to encourage you to seek more "positive" influences within the areas they have censored. You might feel they are being out of order but if you can actually have an adult conversation with them about the whole thing maybe you can reach an understanding of sorts?
Acting out isn't going to help you though - sorry about that
