The Contender (2000)
Joan Allen and her movie Dad, Philip Baker Hall, are both atheists. Even more improbably...almost in sci-fi territory...Allen is playing an atheist, pro-choice REPUBLICAN!1!1
Haven't seen it in a while, but IIRC, Allen mentions that her little boy heard something about Jebus at school. Hall, a lawyer, says something like, "I fought for years to keep that crap out of the public schools." Allen says, "Well, he also still believes in Santa and the Easter Bunny."
Many denizens of R/T would NOT like that movie.
Allen gives this speech to Congress (thanks, IMDB!):
And, Mr. Chairman, I stand for the separation of Church and State, and the reason that I stand for that is the same reason that I believe our forefathers did. It is not there to protect religion from the grasp of government but to protect our government from the grasp of religious fanaticism.
Now, I may be an atheist, but that does not mean I do not go to church. I do go to church. The church I go to is the one that emancipated the slaves, that gave women the right to vote, that gave us every freedom that we hold dear. My church is this very Chapel of Democracy that we sit in together, and I do not need God to tell me what are my moral absolutes. I need my heart, my brain, and this church.
http://www.imdb.com/title/tt0208874/