Not all atheists have revealed their atheism to their friends and neighbors. Religious theism is so widespread, and distrust of atheists so prevalent, that many people can’t tell the full truth even to those closest to them out of fear of ostracism and discrimination. This is a serious indictment against the alleged morality of religion in America today, but it also points to an opportunity: if more atheists did come out of the closet, it might lead to a change in attitudes.

http://atheism.about.com/od/atheistactivism/p/ComeOutFriends.htm?nl=1