Religion is a belief system (such as Christianity, Judaism, Islam, etc.) which generally purports belief in one or more deities.
Farkers tend to fall into one category or another, Rabid Mooslim Hating Xtians and those who aren't. A small number still adhere to the tenets of Pastafarianism.
A place in which religion comes up a lot is in the Politics thread, due in part to so many conservative politicians trying to get the evangelical vote.