I learned that freshman year.
In a group discussion some girl started citing bible verses in reference to the morality of birth control and I went off on her. Went something like this:
Girl - "Life exists at the point of conception"
Me - "I believe life starts at the point of conciousness"
Girl - "There's a verse in the bible that explains this"
Me - "Ok - and you believe that completely?"
Girl - "Why shouldn't I?"
Me - "So then you also believe the world was created in seven days"
Girl - "Well...the head of the church is looking into that...they think days might have been longer back then..."
Girl #2 - "STOP ATTACKING HER!"
As you can see I'm not exactly an advocate of organized religion. I ended up apologising to her afterward.
You're not going to win either way - just put on a happy face and keep the heavy shit to yourself.