Dropping S&S party: good times, Italian food, and God will understand:

If the Lutherans are correct, then you didn’t need the organizational structure of a class to learn about religion anyway.
If the Calvinists are correct, then it was predetermined anyhow and now you know you’re saved.
If the Catholics are correct, it’s fine since you’ve made your confession and feel guilty about it.
If the Unitarians are correct, then since the class wasn’t on Sundays you don’t need to worry about it.
If the Hindus are correct, then you’ll just take the class again later.
If the Jews are correct, then since you’re celebrating with food it’s perfectly kosher.
If the Atheists are correct, then this definitely isn’t a problem.