Boyfriend pressuring me about religion!!

I've been dating this guy for over 2 years now. His family is very religious, which isn't a bad thing, but they're so different from every other religion, and they're pushing it on me. In the beginning of our relationship I wanted to see what they believed, so I went to their church and studied "their Bible" with his mom. After about 6 months I realized that their religion wasn't for me, and I stopped going. While I was going to church with them, they included me in everything, but since I stopped about a year ago, I have not seen them, or been over his house since. Recently, he started pressuring me to start coming to church again. He says he wants to marry me and if I would go to church it would make it easier on him with his family (because his mother hounds him all the time about dating a girl outside their religion). I want to do it to make him happy, but at the same time, I don't. I'm confused. I feel if I start going again, it won't stop at me going once a month. His mother will pressure me to come more, do more, study more. I need advice!