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.

The nation’s new president, Donald Trump, certainly fits this pattern. Trump is the nation’s ninth chief executive to be affiliated with a Presbyterian church. Presbyterianism has its roots in England and Scotland and has been active in North America since the 17th century.

Even though he no longer regularly attends a Presbyterian church, Trump was raised a Presbyterian and still considers himself one, saying “my religion is a wonderful religion.” (As a young man in New York, he began attending Marble Collegiate Church, a Dutch Reformed congregation, and in recent years, he has been associated with Paula White, an evangelical megachurch pastor who will pray at his inauguration.)

The first Presbyterian to occupy the White House was Andrew Jackson and the last, before Trump, was Ronald Reagan. Both Jackson and Reagan had Scots-Irish ancestry. Trump’s mother immigrated to the U.S. from Scotland.

A recent survey by the Pew Research Center shows that many Americans care about their leaders’ faith. For instance, half of all American adults say it’s important for a president to share their religious beliefs. And more people now say there is “too little” religious discussion by their political leaders (40%) than say there is “too much” (27%).

Historically, about a quarter of the 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. Unitarians and Baptists (including Bill Clinton and Harry Truman) are the groups with the third-largest share of presidents, each with four.

Although Roman Catholicism has long been the nation’s largest religious denomination, John F. Kennedy remains the only Catholic president. And since Kennedy’s assassination in 1963, only one other Catholic, John Kerry, has been a presidential nominee on a major party ticket.

Two of the most famous presidents in American history had no formal religious affiliation. The first, Thomas Jefferson, lost his faith in orthodox 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 never joined a church. Scholars have long debated Lincoln’s beliefs, including the question of whether or not 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.

Trump’s predecessor, Barack 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. Today, Obama calls himself a Christian, but is not a regular churchgoer.

Note: This post was originally published on Feb. 12, 2015, and has been updated.

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