"I love Iowa. And, look, I don't have to say it, I'm Presbyterian. Can you believe it? Nobody believes I'm Presbyterian," Trump said at a rally in Florida this weekend. "Boy, that's down the middle of the road folks, in all fairness. I mean, Seventh-day Adventist, I don't know about. I just don't know about."
With that single comment, Trump sought to halt Carson's rise in the polls by suggesting his Seventh-day Adventist faith is outside the mainstream -- a significant charge in Iowa, where evangelical voters play a big role in the first-in-the-nation caucus.
Carson has spoken openly about his relationship with the Seventh-day Adventist church and how his faith has influenced his approach to politics. That's especially important because Carson's religious background could carry the power to connect with evangelicals. But it could also be a liability if Trump and others are able to depict his denomination as being at odds with mainline Christianity.
Carson speaks powerfully of the benefits of faith and how religion can bring together communities that would otherwise be divided. But he also has a history of offending people who don't share his religious values, including comments last month in which he said he didn't think a Muslim should be president.
In an interview with CNN in September, Carson spoke about the complexities of his faith and said there are misconceptions about the Seventh-day Adventist Church.
"People tend to ascribe to Adventism any weird thing they have heard about religion because they don't really know," Carson said. "Adventism believes the entirety of the Bible."
He described himself as "not a real religious person."
'Deep and abiding faith'
"I'm a person who has a deep and abiding faith and relationship with God," he said. "But I'm not really into a lot of religious dogma and rituals -- 'you can't do that, and you can't do this.' I don't believe in that. I believe you have to have a deep and abiding faith in God."
Carson is one of the 18 million Seventh-day Adventists around the globe. The church, the most diverse in the country, counts 1.2 million members in North America and about one third are African-American. Strict and health-conscious -- many believers are vegetarians -- the denomination has attracted 1 million new members each year for the last decade.
Yet, almost just as many have left the pews.
"They are in many ways like conservative evangelicals, no same-sex marriage and no abortion," said Anthea Butler, a religion professor at the University of Pennsylvania. "It's a 19th-century religion that comes out of a space where health and holiness was important. But they have this leader who is a woman, Ellen G. White, and they veer off of traditional mainline Christianity."
White, whose visionary writings are still a staple of church teachings, co-founded the church in 1863, almost two decades after predictions of the second coming of Christ turned out to be premature in 1844. The return of Christ remains central to the doctrine.
Carson said his beliefs about Muslims and Sharia law aren't backed up by teachings of his church, although they are in keeping with what some conservative evangelicals believe.
"This is him pandering," Butler said. "He is not with them right now, he is trying to emulate (Mike) Huckabee," referring to the pastor and former Arkansas governor who is also seeking the GOP presidential nomination.
She added: Adventists "are not politicians. That is not their thing."
As a boy, Carson heard the spiritual and vocational calling that shaped his life.
One Saturday, he sat in the pews of a Seventh-day Adventist church in Detroit and listened to a sermon about robbers chasing a missionary doctor and his wife. The couple escaped, finding refuge in "the cleft of the rock, and God protected them from harm," Carson recalled his preacher saying.
"Although I was only 8, my decision seemed perfectly natural," he wrote in his 1996 memoir "Gifted Hands." "Other kids my age were getting baptized and joining the church, so when the message and music touched me emotionally, I responded."
He was baptized again when he was 12. And at 14, he learned the strength of God's transformative power, after his temper flared and he attempted to stab a friend for changing the station on a transistor radio. Filled with rage, Carson aimed his camping knife at his friend's stomach, but landed on a heavy belt buckle instead. The knife broke in half; Carson ran home.
In the Tuesday speech at Cedarville University in Ohio, he retold the story, recalling how he poured over the Bible in the bathroom, landing on Proverbs.
"When I came out of that bathroom after three hours, the temper was gone," he said. "And some people say you just learned how to hide it. When God fixes a problem, he doesn't just do a paint job, he fixes it from the inside."
The story is a staple of many of his speeches, doubling as an expression of faith and in some ways a critique of big government liberalism -- you can pray, and think, your way out of poverty and bad habits, Carson has said.
On taxes, he borrows from Scripture for his 10% tax plan. His flat-tax plan would simplify the current tax code by basing it on tithing. As Christians are urged to tithe 10% of their income, taxpayers would pay 10% of their income.
"I want a system that's based on biblical principles, because it seems to me that God is pretty fair," he said in Phoenix in August.
And when Carson rails against political correctness, as he did after his statement about the Muslim faith, he is echoing the language of church leaders.
At an October 2014 speech, Ted N.C. Wilson, the church's president, told his congregation that the "devil is attempting to neutralize God's church," in what the church believes are the closing hours of Earth's history.
"Stay away from anything that will undermine our message or cloud our distinctive beliefs. Don't be tempted by the devil to blend in with the crowd or be 'politically correct,'" he said. "Don't proclaim a 'generic' Christianity or a 'cheap-grace Christ' which does not point to the distinctive biblical truths to be declared worldwide -- the very reason for which the Seventh-day Adventist Church was organized."
Yet, for much of the church's history, members have been ambivalent about politics and politicians. The church's North American division issued a statement in May when Carson announced his presidential bid reminding members and pastors of the official position on the separation of church and state.
"Adventists should not, however, become preoccupied with politics, or utilize the pulpit or our publications to advance political theories," the statement read.
There are two Adventists now serving in Congress: Reps. Sheila Jackson Lee, D-Texas, and Raul Ruiz, D-California, who, like Carson, is a physician.
But for Adventists, political ambivalence is built into the doctrine. Church theology teaches that in the end days, the federal government will mandate Sunday church attendance, giving all who comply the "mark of the beast."
Church members are slowly expanding their reach into politics, even as some skepticism remains. This summer, a handful of Seventh Day Adventist political leaders gathered to launch a networking and support group.
"You are the Esthers, the Josephs, the Daniels of our world," Wilson urged his flock during the meeting, according to the Adventist News Network. "You make a difference in an arena that most of us never touch. And never forget you are there for a purpose; you are where God has placed you. Yes, you serve your country, or a particular legislature. But most importantly, because you are a Seventh-day Adventist, you are working under the very highest authority: Jesus Christ our Savior. You are called to be unusual ambassadors for Christ."
For his part, Carson has framed his entry into politics as ordered by God.
"Lord, if you want me to do this," he said recently, referring to his prayerful thought process on a presidential run, "you have to open the doors. And if you open the doors, I will gladly walk through them."
Asked about his role as the most high-profile Adventist politician, Carson rejected the label, and pointed to the Scripture.
"I look in the Bible and I see Joseph who became the governor of Egypt, I see Daniel," he said in the interview with CNN. "I don't see any biblical reasons you wouldn't do that if you have a goal of improving the situation for everybody."
David Holland, a Harvard professor who is working on a book about White, said Carson is "both a symptom and cause of the evolution of the thinking and the culture" of Adventists being involved in political life.
"Any time a member of a group that has often been marginalized achieves this kind of prominence and attracts this kind of spotlight, it creates a moment of self-reflection over what it means to participate at the highest level of government and how they square that with the faith," Holland said.
The professor added that it makes sense that the first major Adventist political figure is a doctor, "because that's been such a critical part of their contribution to the world."
Adventist Health System is one of the largest, non-profit hospital systems in the country.
Mixing faith and politics has proved tricky for Carson -- often in unexpected ways. Carson has drawn fire from evangelicals for writing on his Facebook page that while Muslims, Jews, and Christians differ on Jesus, they "all believe in God," and are "all God's children."
Butler added that, as with Mitt Romney's Mormonism, Carson's Seventh-day Adventism could pose a problem among some orthodox evangelicals.
"Some Christians don't think of them as Christians because they are extra-biblical," she said. "They look at the Bible but they revere the teachings of Ellen G. White."
Indeed, in April, the Southern Baptist Convention pastor's conference rescinded their invitation to Carson over political and theological concerns. A group of pastors wrote of their objections: "Dr. Carson is a Seventh-day Adventist. Their official theology denies the doctrine of Hell in favor of annihilation, denies the doctrine of Sola Scriptura, and believes that those who worship on Sunday will bear the 'mark of the beast.'"
The church says that adherents "accept the Bible as the only source of our beliefs" and affirm the Christian doctrine of Sola Scriptura, the idea that the Bible is the sole source of authority on beliefs and practices. Carson brushed off the criticism and said he had just as many evangelical pastors supporting him.
"When you get into the ins and outs of every denomination you can be picking at each other till the end of times about things you shouldn't be worried about," he said.
For decades, Carson, whose life story and medical career embody teachings around personal responsibility and health, has been a celebrated figure among Adventists. His memoir is a staple of Adventist schools and he has been a frequent speaker at church-affiliated hospitals. In shifting his attention to electoral politics, Carson is gaining a new and different audience, yet leaving some members questioning his path.
"The religious right is pretty generally viewed with suspicion among Adventists. They want someone who is more thoroughly libertarian as opposed to someone who is going to be pushing heavily a moral agenda through politics," said Douglas Morgan, an Adventist and a professor of history at Washington Adventist University. "Some are enthusiastic but it's a small minority. I don't get much of a sense from Adventists that this is our man, this is our Adventist candidate."
Carson said he has found plenty of support among fellow members of his church and the criticism doesn't bother him at all.
"I don't identify myself as an Adventist," he said. "I identify myself more as an American who happens to believe in Christ."