20th on 21 interesting Facts About the U.S.A:After Christianity, the largest religious affiliation in the U.S. is Judaism.
After Christianity, Judaism is the next largest religious affiliation in the US, though this identification is not necessarily indicative of religious beliefs or practices. There are between 5.3 and 6.6 million Jews. A significant number of people identify themselves as American Jews on ethnic and cultural grounds, rather than religious ones. For example, 19% of self-identified American Jews do not believe God exists.