From Gospel Coalition:
The Story: A new study finds that the typical American believes the United States is far more religiously diverse than it actually is, overestimating the number of Mormons and Muslims and underestimating the number of Protestants.
The Background: Grey Matter Research surveyed American adults and asked people to estimate what proportion of Americans are part of or affiliated with eight major faith perspectives: Protestant (including Baptist, Lutheran, Methodist, Presbyterian, Pentecostal, and all other Protestant groups), Catholic, Jewish, Mormon, Muslim, atheist or agnostic (don’t believe in God or don’t believe we can know whether there is a God), believe in God or a higher power but have no particular religious preference, and any other religious group.
According to the study, the typical American adult estimates the religious affiliation in the U.S. as follows: 24% Catholic, 20% Protestant, 19% unaffiliated, 9% Jewish, 9% atheist or agnostic, 7% Muslim, 7% Mormon, and 5% from all other religious groups.
The typical American badly underestimates how many Protestants there are in the country, notes the report, and overestimates the presence of religious minorities such as Mormon, Muslim, and atheist/agnostic.