How do I deal with my mom disliking the genre of music I like?

Just tell your mom the truth dude. Tell her just becuase the band are atheist, it does notmean it will affect you. Take me for example. My favorite band, and has been for six years now, is Muse. The members used to be athiest, now they are agnostic. They have a song called Fury: "And we'll breathe in, cleanse away our sins, and we'll pray, that there is no god, to punish us, and make a fuss". I sing along to all of Muse's songs, including Fury, and I am a devout Catholic! It is up to you to decide what influnces you dude, and your mom ha to relaize that. if your Faith and whatever is strong, then a band wont change that. You should probably confess that you didn't see Demi too. Lol. Anyways, alternative music is always, ALWAYSbetter than pop. haha. Good luck.