Jimmy Carter was the first American president to describe himself as “born again,” which today is a somewhat strange term for experiencing rebirth through a personal relationship with Jesus Christ.

It was more of a process than a one-time experience, said the former president, who spoke frequently and fluently about his Christian faith throughout his life and was honored at a state funeral on Thursday.

“There was no rebirth when I was 11,” he wrote in his 1996 book “Living Faith.” “For me it was an evolutionary thing. Instead of a flash of light or a sudden vision of God speaking, it was a series of steps that brought me ever closer to Christ.”

Mr. Carter, a liberal Southern Baptist who advocated for civil rights and equality, was treated as something of an oddity by the East Coast press when he burst onto the national stage. Newsweek published a cover story on his campaign in 1976 entitled “Born Again!” The Evangelicals.”

And his statements about his faith sometimes sparked confusion, such as when he told interviewers for Playboy that year that he had “committed adultery in my heart many times” and had “looked at many women with lust,” referring to the words Jesus referred to sin in the book of Matthew. (In the same extensive interview, he quoted theologians Reinhold Niebuhr on the purpose of the law and Paul Tillich on religion as a lifelong search for truth.)

“Carter’s Comments on Sex Raise Concern,” headlined the New York Times, reporting that Mr. Carter’s “down-to-earth comments” — he used language some found rude in discussing adultery — posed a problem for the election could represent him, although two months later he prevailed against the incumbent Gerald Ford.

As president, Mr. Carter’s faith was not enough to endear him to the emerging Christian right. Prominent conservative pastors and radio and television hosts portrayed him as weak in defense and meek about what they described as a threat to “family life.”

Conservatives may have shared Mr. Carter’s theology and biography as a Southern evangelical Christian, but he was not considered one of them. Instead, they coalesced around Ronald Reagan, a divorced former actor who rarely attended church and who routed him in the 1980 election.

Mr. Carter also struggled with the religious tradition in which he was raised.

In 1976, his Baptist church closed its doors and canceled Sunday services rather than admit black worshipers, a policy Mr. Carter opposed. His current congregation, Maranatha Baptist Church, was founded soon after by unhappy members who wanted a more inclusive place of worship.

And in 1990, he distanced himself from the Southern Baptist Convention over the denomination’s approach to women in leadership positions.

But Christian faith remained a defining theme for Mr. Carter, who enjoyed the longest post-presidency in American history. He became known for his charitable work, including with Habitat for Humanity, a Christian housing organization, and he taught a Sunday school class for years and regularly drew crowds to his hometown of Plains, Georgia, especially after he announced his cancer diagnosis in 2015.