While Donald Trump has managed to win over many evangelical Protestants, he has failed to catch fire among Mormons.

In fact, Trump is so unpopular among Mormons that some polls suggest that Utah – the only majority-Mormon state – will go for Evan McMullin, a third-party Mormon candidate largely unknown in the rest of the country.

And even if Trump does take Utah, it will be with a fraction of the support a “generic” Republican would have been expected to receive.

The evangelical-Mormon disconnect may seem puzzling, given that both groups are culturally conservative and heavily Republican. Indeed, it may seem all the more puzzling given that Mormons are the most Republican religious group of all.

So why has Trumpism failed to catch fire among Mormons? Based on research I’ve done with John Green and Quin Monson for our book “Seeking the Promised Land: Mormons and American Politics,” there are three reasons why Mormons oppose Trump: the wall, the ban and the man.

The wall

The first explanation for Mormons’ lack of support for Trump is his rhetoric on immigration, including their resistance to his promise to build a wall along the U.S.-Mexico border and their unease with Trump’s anti-immigrant rhetoric.

As we argue in “Seeking the Promised Land,” Mormons are far more sympathetic to immigrants than other politically conservative groups.

This is true for Mormons across the board, but especially among the roughly one-quarter of LDS church members who spend up to 24 months serving as full-time missionaries between the ages of 18 and 22. Young missionaries may go abroad or serve in the United States among an immigrant population. A positive view of immigrants is even more pronounced among the 15 percent of Mormons who learn to speak a language other than English during their missionary service.

This pro-immigration sentiment is reflected in and reinforced by the rhetoric and action of the Church of Jesus Christ and Latter-day Saints, which has consistently been a voice of moderation on immigration policy. To many Mormons, a humane policy toward both documented and undocumented immigrants – including keeping families intact – is a religious imperative.

Not to mention the fact that Latinos are an ever-increasing share of the global Mormon population. Here in the United States, the percentage of Mormons who are Latino is 7 percent and growing.

The ban

The second reason why many Mormons oppose Trump lies in his vitriolic language toward Muslims, as exemplified by his call for a ban on Muslims entering the U.S.

As we report in our book “American Grace,” Robert Putnam and I have found that Mormons have a high regard for Muslims, as they do for all other religious groups.

Even more important is Mormons’ sensitivity to the dangers of animus directed toward a fellow religious minority. Mormon leaders underscored this point by releasing a statement in December 2015 that was a thinly veiled swipe at Trump’s anti-Muslim comments. They quoted Mormon founder Joseph Smith as saying that:

“for the same principle which would trample upon the rights of the Latter-day Saints would trample on the rights of the Roman Catholics, or of any denomination who may be too unpopular or weak to defend themselves. It is a love of liberty which inspires my soul – civil and religious liberty to the whole of the human race.”

In case one thinks that Muslims were somehow not included in this sentiment, in 1841 the city of Nauvoo, Illinois – the headquarters of Mormonism at the time – explicitly mentioned “Mohammedans” (that is, Muslims) in a statute guaranteeing “free toleration and equal privileges.”

Nor is this merely fusty language from the past. The principle of religious tolerance runs deep within Mormonism today, as many Mormons have personally experienced the ugliness of religious bigotry. Robert Putnam and I have found that Mormons are among the groups most likely to report hearing disparaging remarks about their religion, and are among the religious groups that are viewed most negatively by Americans of other faiths. This was underscored by the hostility directed toward Mitt Romney during his first run for the presidency in 2008.

The man

While the wall and the ban matter to Mormons, these two issues do not fully explain why Mormons and evangelicals have diverged in their opinions about Donald Trump. After all, many evangelicals are also sympathetic to immigrants and concerned with religious freedom. Perhaps even more than the wall and the ban is the man – Mormons’ strongly negative reaction to the revelations regarding Trump’s past behavior, especially his sexual misconduct.

A recent poll by the Public Religion Research Institute and Brookings has shown that 72 percent of evangelicals believe that an immoral person can nonetheless behave ethically when fulfilling public duties, a stunning increase from only 30 percent five years ago.

That same poll did not break out the results for Mormons, but there is every reason to think that they differ sharply on this point. For Mormons, the importance of personal rectitude is paramount – including, and perhaps even especially, for elected leaders.

Mormon scripture, for example, includes this statement, believed by Mormons to be the literal word of God,

“When the wicked rule, the people mourn. Wherefore, honest men and wise men should be sought for diligently, and good men and wise men ye should observe to uphold; otherwise whatsoever is less than these cometh of evil.”

This sentiment is regularly reinforced by Mormon leaders in modern times.

While back in the 1800s, Mormons’ now abandoned practice of polygamy gave them the reputation for moral licentiousness, today Mormons hold a strict view on sexual morality – 94 percent of Mormons with a high level of religious commitment morally disapprove of sex between unmarried adults. Thus, one can see why many Mormons would be wary of voting for a presidential candidate who has been heard bragging about his extramarital sexual activity, including his infamous boast of committing sexual assault.

Mormons’ unease with Donald Trump, however, does not mean that they have flocked to Hillary Clinton. They are, after all, a strongly Republican and deeply conservative group, and thus unlikely to vote for a Democrat. Instead, many Mormons have apparently decided to cast what is essentially a protest vote for third-party candidate Evan McMullin – who is both Mormon himself and a conventional conservative. McMullin will not win the presidency, or perhaps even the state of Utah, but in voting for him many Mormons will feel that they have avoided selecting from the lesser of two evils.