Members of The Church of Jesus Christ of Latter-day Saints have the largest families in America, among both religious and nonreligious groups.

Second place goes to Muslims, according to a survey released Monday.

The "U.S. Religious Landscape Survey" was prepared by the Pew Forum on Religious and Public Life, based in Washington, D.C. The forum is funded by the Pew Charitable Trusts.

The survey's summary says, "No matter how rigorous, however, all surveys have their limitations and the Landscape Survey is no exception. ... These limitations are particularly apparent when it comes to providing definitive figures on membership in religious groups."

That seems to skew the membership figures for the LDS group downward. The survey was conducted only among adults 18 and older, and many LDS families have children under 18, as evidenced by the finding that members of the church have the largest families.

Also, the results only include members of a religion who live in America, while the LDS membership is worldwide.

Chief findings are that 78.4 percent of the sampling of 35,000 Americans say they are Christians. The study found that 51.3 percent of all Americans are Protestant, 23.9 percent are Catholic, 1.7 percent are LDS, Jehovah's Witnesses make up 0.7 percent, Orthodox Christians are less than 0.6 percent and other Christians are 0.3 percent.

Last July, the U.S. population was about 301.6 million, according to the U.S. Census Bureau. If the survey is accurate, the LDS faith's membership in America would amount to more than 5.1 million adults.

About 1.7 percent of Americans are Jewish, 0.7 percent are Buddhist, 0.6 percent are Muslims, 0.4 percent are Hindu, other world religions are less than 0.3 percent.

Unaffiliated make up 16.1 percent of Americans, including atheists (1.6 percent), agnostics (2.4 percent), "nothing in particular" (12.1 percent) and religious but unaffiliated (5.8 percent). Those who said they didn't know or refused to answer were 0.8 percent of the sampling.

Key findings include:

• Members of the LDS Church have the most children living at home. Mormon households with four or more children are 9 percent of the membership, compared with 3 percent nationally. Runners-up are Muslims, with 6 percent. Only 4 percent of Catholics have four or more children.