Freedom of Religion = Free to be Atheist?

Either I'm on an atheism trend or the media is because I keep running across interesting news on atheism.  This letter to the editor points out that while there is freedom of religion in the United States, our founders clearly believed that everyone would believe in God.  Our currency says "In God We Trust."

I would argue that there are philosophies like Buddhism could qualify as religions and they don't believe in "God."