My mom won't let me date anyone outside of my religion?

I like this guy, he likes me. My dad would be okay with us dating, but not my mom. She only wants me to date people of my religion, even though I'm not that involved with my religion. I'm 18 and today she came out and stalked me because I was an hour late coming home from working out. She doesn't like the guy that I like, and she biased herself against him in her own little world even though she doesn't even know him. I've never done anything wrong... I haven't gotten drunk, never been to parties, never did drugs, never smoked, never had sex, I haven't even had a bf or my first kiss yet! And she doesn't trust me at all! It really sucks ): I like him a lot and we can't do anything because it would be awkward and complicated. What do I do? ): My mom is always mad at me for talking to him or hanging out with him because she thinks I'm not "loyal" to her anymore. She needs to give me some space!! ):