take your personal radio and listen to the sport like homer simpson!
Personally if it meant a lot to her i would go. I am not religious but i have my moments - deaths, ill friends/relatives etc. You mentioned before you are planning on getting married and if you plan to get married in a chuch then not going at easter because you don't believe in it makes you a bit of a hypocrite.
If you really don't want to go tell her and explain why. Maybe she sould settle for you dropping her off and then picking her up afterwards and then doing something afterwards.