Americans overstate size of religious minorities

The typical American underestimates how many Protestants there are in the United States and vastly overestimates the size of religious minorities such as Mormons, Muslims and atheist/agnostics, according to a new study.

Grey Matter Research and Consulting asked 747 U.S. adults to guess what proportion of the American population belongs to each of eight major religious groups: Protestant, Catholic, Jewish, Mormon, Muslim, atheist/agnostic, those who believe in God or a higher power but have no particular religious preference, and members of any other religious group.

The average response was that 24 percent of Americans are Catholic, 20 percent are Protestant, 19 percent are unaffiliated, 8 percent are Jewish, 9 percent are atheist or agnostic, 7 percent are Muslim, 7 percent are Mormon and 5 percent identify with various other religious groups.