How do I tell my southern baptist parents that my girlfriend is atheist and so am I?

I'm 20 and started dating a girl about a month ago who is atheist. I have been an atheist myself for over a year now but every time I've tried to suggest that I don't believe in god my parents freak out and pound religious bullshit into me until I tell them I believe it. Now they're pressuring me to bring my girlfriend to church and I don't want to do it. My girlfriend said she'd do it just so they'd be happy, but I don't like doing shit just to appease others make believe feelings. How do I get around this? How can I break the news?