Help! I have horrible roommates -- LiveWire College Forums

Well, to start off, I'm originally from California, and so to me, Religion is different than it is out here in good old Georgia. When I came over here, the person that I was moving in with knew for a fact that I wasn't a Christian like she was, and she was fully accepting of that. Well a month into our living together she took a trip to Israel with her grandmother who is a pastor of a church. When my roommate got back, she went insane on me! She tried and tried to convert me, and finally I just started acting like I was actaully listening to what she was saying. She accepted the fact that she thought that she actually converted me and everything. Recently is when the bigger problems started arising between us (and the third roommate that just recently moved into our apartment with us.
Now see, before I was a push over because I'd go out and buy food, my roommate would eat it, I wouldn't say anything and I'd just go buy more. It kept going on like that for a while, and currently it's still going on. I let that slip, I also let slip the fact that I was the one taking care of her dog for her, and also cleaning up dishes and everything for her while she was out or just messing around in the apartment. Recently, I feel that my roommate crossed the line. Lately I've been hanging out with a really good guy friend of mine and I'd been spending the night over there because we'd hang out and it'd get too late for me to drive home or we'd drink and I don't want to drive while intoxicated. Well since I was always out, my roommates thought I was sinning, and so one night when I was at my apartment, one of my roommates lectured me on the fact that they felt that I was acting slutty by hanging out with guys so much. It's not my fault I get along better with guys than with girls. The biggest problem is the fact that my two roommates took it upon themselves to go into my bedroom and put oil crosses all over...but the one thing that infuriated me was the fact that they put oil crosses all over the face of the guy that I'm interested in. My two roommates think he's a bad influence, even though they don't even really know him that much. The oil messed up the two pictures that I had of him...
I want to confront them and let them know that it was crossing the line to mess up my personal stuff for their own pleasure, but I'm not sure how to bring it up without them making me look like the bad person. (they have a tendency to do that). Any ideas on how to solve this problem?

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Derrick C can drift his way into my heart anyday.