As the 2016 presidential campaign heats up, many of the Republican potential hopefuls have strong Christian convictions.

Sen. Ted Cruz, who is announcing his candidacy Monday, and former Arkansas governor Mike Huckabee are Southern Baptists. Wisconsin Gov. Scott Walker, a nondenominational evangelical, and neurosurgeon Ben Carson, a Seventh-Day Adventist, also are devout Christians. Several of the potential contenders are Catholic, including former Florida governor Jeb Bush, Sen. Marco Rubio, Louisiana Gov. Bobby Jindal and former senator Rick Santorum.

As recently as 1960, American voters were very concerned about the Catholic faith of John F. Kennedy. Fears that Kennedy would take orders from the pope caused consternation for many voters in that year’s presidential election, and New York Gov. Al Smith’s Catholic faith contributed to his defeat in 1928. What once seemed to potentially disqualify a candidate appears to be off the table, at least for those who are Catholic.

So could atheists have their JFK moment soon?

Clearly the landscape has changed. 90 percent of Americans believe in God, although scholars who track trends in religion are watching how the rising number of “Nones” — those who do not identify with any religion — may impact the religious landscape. Today they constitute 20 percent of all American adults. About 13 million (nearly 6 percent of Americans) describe themselves as atheist or agnostic, while 33 million people (14 percent) report that they have no particular religious affiliation. However, nearly 95 percent of those with no religious affiliation also say they believe in God, and about half of them say they are “spiritual” but not “religious.”

Given this increase in “nones,” especially among younger adults (one-third of all adults younger than 30 are religiously unaffiliated), could an atheist perhaps be elected president? Probably not. In a 2014 Pew Research Center poll, twice as many religiously unaffiliated Americans said they would be less likely to vote for a candidate who does not believe in God (24 percent) as said they would be more likely to do so (12 percent). Most (64 percent) stated that a candidate’s atheism would not matter.

It appears that an overt atheist would have more difficulty being elected than Barack Obama did in becoming the nation’s first black chief executive or a woman or gay candidate would have in winning the White House. In numerous surveys, at least half of Americans state that they would not vote for an atheist. While the numbers of those who declare that they would not vote for an atheist have declined in the new millennium, a 2014 Pew Research Center poll found that Americans are less likely to vote for an atheist than any other type of candidate, including ones who have never held office, have had extramarital affairs, are in their 70s or are gay.

Being identified as an atheist in the United States today is still such a major political liability that a candidate holding this position probably could not gain a major party’s nomination for president or even the Senate. Only eight members of the current Congress declined to indicate their religious affiliation, and only one of them, Rep. Kyrsten Sinema (D-Ariz.) identifies herself as religiously unaffiliated.

Atheists in other countries have had more success. In 2010, Julia Gillard became Australia’s first female and first unmarried prime minister. Even more remarkably, she won Australia’s highest office after openly declaring that she is an atheist. Although Gillard is no longer in office, 10 other popularly elected heads of state are self-described atheists, agnostics, or nonbelievers, including President Francois Hollande of France, President Milos Zeman of the Czech Republic, Prime Minister Elio Di Rupo of Belgium and Prime Minister John Key of New Zealand. Granted, Europe and Oceania are more secular than the United States. More striking is the fact that South Korea (which has a sizable Christian population) and two historically Catholic countries — Uruguay and Chile — also have elected presidents who identify themselves as atheists or agnostics.

The religious affiliation of presidents has clearly mattered to many Americans throughout history, as about half (19) of the nation’s presidents have belonged to two prominent denominations: the Episcopal Church and the Presbyterian Church.

On the other hand, Americans have elected presidents who belonged to non-mainline traditions, most notably four Unitarians (and only one of them — William Howard Taft — faced opposition because of his faith) and two Quakers (Herbert Hoover and Richard Nixon) despite the denomination’s historic pacifism. A religiously unaffiliated individual (Andrew Johnson) and two men who had never joined a church (Abraham Lincoln and Dwight Eisenhower) also were elected to the nation’s highest office.

The only candidate in American history charged with being an atheist — Thomas Jefferson — was handily elected in 1800. Federalists repeatedly attacked him as an infidel who would destroy the nation’s Christian foundations and staunchly promote secularism. Several factors kept Jefferson from being defeated. Most important, the accusations were false — he believed in God, repeatedly affirmed God’s providence, and frequently worshiped in Episcopal churches, so many discounted these attacks as mere political partisanship. Jefferson also was popular and highly respected for his previous political service.

What about today? Have the presidential prospects of atheists and agnostics improved? In some ways they clearly have. In several bestselling books, Sam Harris, a neuroscientist, attacks Christianity, tries to supply a secular basis for morality, and provides a scientific foundation for spirituality. He also argues that countries like Scandinavian ones that are much more secular than the United States have much lower rates of many social ills, including crime, drug use, teenage pregnancy and poverty.

In the aftermath of the tragic shootings at an elementary school in Newtown, Conn., in 2012, Susan Jacoby, author of “Freethinkers: A History of American Secularism,” urged atheists to provide consolation to mourners who believed that “their lives have meaning even if they do not regard death as the door to another life, but ‘only perfect rest.’ ” She and others urge atheists to create community-based outreach programs to work for social change and make their cause more publicly visible. They hope to change popular perceptions that atheists lack empathy and kindness. Similarly, secularists have undertaken campaigns to argue that people can be “good without God.”

So why would it be so difficult for an atheist to be elected president? First, many Americans perceive atheists to be untrustworthy, insensitive and morally rootless. Despite their recent campaign to improve their image, a 2014 Pew poll found that Americans rated atheists more unfavorably than any religious group including Muslims. Second, in other polls, most respondents (as many as 72 percent) said they want the president to have strong religious beliefs. Many Americans also say they want presidents to seek God’s guidance about the major decisions they must inevitably make.

During the 1988 campaign, Rob Sherman of American Atheists said he asked George H.W. Bush at a campaign stop in Chicago what he would do to win the votes of atheists. Bush replied that he would do little because “faith in God is important to me.” Sherman countered, “Surely you recognize the equal citizenship and patriotism of Americans who are atheists.” “I don’t know that Atheists should be considered as citizens,” Bush declared, “nor should they be considered patriots. This is one nation under God.” It is hard to imagine another presidential candidate making such remarks in this age of ideological pluralism, political correctness and emphasis on civility. Also, the public image of atheists has improved, but it still lags behind that of most other groups.

Would Americans actually refuse to vote for an atheist candidate if they were impressed by his or her political experience, policies and personality? If Americans had been asked the generic question in 1980 — would you vote for a divorced former Hollywood actor for president? — many would have said no. That year, they voted in droves for Ronald Reagan.

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