A survey by the Pew Forum on Religion & Public Life shows that atheists and agnostics, followed by Jews and Mormons, know the most about religious beliefs.
Four in 10 Roman Catholics didn't know their church teaches that the bread and wine used at communion become the body and blood of Jesus during the eucharist.
The survey also found that graduates of private schools did better than students in public schools.
But religious school graduates didn't fare any better in their ability to answer questions about the Bible, world religions or the role of religion in public life.
© 2014 Augsburg Fortress, Publishers