Much has been written about President Joe Biden’s Catholic faith. He often speaks of his religious convictions and quotes the Bible, and he attends Mass regularly.

Although about one-in-five U.S. adults are Catholic and Catholicism has long been one of the nation’s largest religious groups, John F. Kennedy was the only Catholic president until Biden was sworn in on Jan. 20. Aside from Biden, only one other Catholic, John Kerry, has been a presidential nominee on a major party ticket since Kennedy’s assassination in 1963.

This analysis is an update to posts published in 2015 and 2017 about the religious affiliation of U.S. presidents. Data for this post was compiled from news reports and uses information from the Miller Center, the University of Virginia, PBS’s God at the White House and the Harry S. Truman Library and Museum.

The U.S. Constitution famously prohibits any religious test or requirement for public office. Still, almost all of the nation’s presidents have been Christians and many have been Episcopalians or Presbyterians, with most of the rest belonging to other prominent Protestant denominations.

Faith at the White House: Religious affiliation of U.S. presidents

One-in-five U.S. adults say it is “very important” for the president to have strong religious beliefs, and 14% say it is very important to have a president who shares their own religious beliefs, according to a February 2020 Pew Research Center survey. A far higher share (63%) say it is very important to have a president who personally lives a moral and ethical life.

The previous president, Donald Trump, was included as a Presbyterian in a previous version of this analysis, but he said in an October 2020 interview with Religion News Service that he no longer identifies as a Presbyterian: “I now consider myself to be a nondenominational Christian.”

Historically, about a quarter of presidents – including some of the nation’s most famous leaders, such as George Washington, James Madison and Franklin Roosevelt – were members of the Episcopal Church, the American successor to the Church of England. Presbyterians are the next largest group, with eight presidents, including Andrew Jackson and Ronald Reagan. Unitarians and Baptists (the latter including Bill Clinton and Harry Truman) are the groups with the third-largest share of presidents, each with four. There also have been four presidents who identify as Christian without a formal denomination, including Trump and his predecessor, Barack Obama.

Obama was raised in a nonreligious household but converted to Christianity as an adult and worshipped at a United Church of Christ congregation – Trinity United Church of Christ – in Chicago. However, Obama left Trinity during his first presidential campaign in 2008 after controversial statements by the church’s senior pastor, Jeremiah Wright, gained widespread attention.

Two of the most famous presidents in American history had no formal religious affiliation. The first, Thomas Jefferson, lost his faith in traditional Christianity at an early age but continued to believe in an impersonal God as the creator of the universe. Jefferson famously edited the New Testament by removing references to the miracles and leaving in Jesus’ teachings.

The second, Abraham Lincoln, was raised in a religious household and spoke frequently about God (particularly as president), but he never joined a church. Scholars have long debated Lincoln’s beliefs, including the question of whether he was a Christian, and some aspects of his faith remain a mystery.

Lincoln is not the only president for whom there is some uncertainty surrounding his affiliation and beliefs. Some presidents were more private than others about their religious leanings, and some may have evolved in their beliefs during their life.

For example, Lincoln’s second vice president and ultimately his successor, Andrew Johnson, identified himself as a Christian but never was formally part of a denomination or congregation. Another 19th century president, Rutherford B. Hayes, sometimes attended Methodist churches but “moved among Protestant denominations during his life,” according to the Berkley Center for Religion, Peace & World Affairs at Georgetown University.

Note: This post was last updated on Jan. 20, 2017.

Aleksandra Sandstrom  is a senor copy editor focusing on religion at Pew Research Center.