This actress is best known for her roles in Go, The Sweet Hereafter and eXistenZ, John Adams miniseries on HBO, and My Life Without Me.
In an interview with Toronto Life, dated October 2006, Polley explicitly refers to herself as an atheist:
"When asked what directors she admires, Polley talks about Ingmar Bergman and Terrence Malick (she says his Thin Red Line “single-handedly brought me out of a deep depression. It shifted something in me. I’m an atheist, but it was the first time that it gave me faith in other people’s faith”)."
A biography at a fan page (written by Ryan C. Niman) includes a section on Polley's religion, or rather the apparent lack of it:
Sarah states that there isn't presently a spiritual side to her life. She once went through a Buddhist stage though. "I think there was a time, probably close to when my mom died, that I became very stringent. I read a lot about Buddhism and I became a sort of Zen....I might still be a Buddhist." Her faith is definitely down to earth, however. "I don't have faith in anything but my fellow human beings and the world around me. I have strong faith in people, but not beyond people. The world is a beautiful place, it's a beautiful enough place for me to worship and have faith in and--it's enough for me."
The source here is: Ehm, Erica. 1994. She Should Talk (Toronto: Harper Collins Publishers Ltd.)