The national poll of 326,271 people over age 18, conducted Jan. 2 through Nov. 30, found just over half of the country -- 51.9 percent -- identifies as Protestants or some other non-Catholic Christian religion, 23.3 percent identifies as Catholic, and 2.1 percent as Mormon, Gallup reported.
People who said they identify as Jewish make up 1.7 percent of the population, and Muslims make up .6 percent, the poll found. Eighteen percent of respondents said they are either do not have a religious identity or chose not to respond to the poll.
Mormons consider themselves the most religious, with 87 percent saying religion is important in their daily lives and 81 percent saying they attend religious service regularly, the poll found.
Of people who said they identified with a religion, Jewish people seemed to be the least religious, the poll found -- with 41 percent saying religion is important in their daily lives and 34 percent saying they attend religious service regularly.
The poll had a margin of error of 1 percentage point.