How can you tell someone you don't want to go to church without being rude?

Recently my girlfriend’s mom has been making her and I go to church. i have never been Catholic, my parents tried to force it on me as a kid and it just pushed me away from it. now i don’t really want anything to do with it. So i told my girlfriend Im not going today and her mom got mad. Is there a better way to handle this situation? How?