The Newt Gingrich who talks about finding ways around the U.S. Supreme Court ban on school prayer and says public schools should be required to “teach the Creator” is not immediately recognizable to those who knew the former House speaker when he was not much of a church-goer. These days, Gingrich is running an overtly faith-based presidential campaign with echoes of televangelist Pat Robertson’s run in 1988.

But on a quieter tour of Catholic America that began more than a year ago, the GOP candidate has been sounding religious themes for some time. Since 2010, Gingrich and his third wife, Callista, have been showing their documentary film about Pope John Paul II, “Nine Days that Changed the World,” in Catholic churches and schools across the country. And as an announcement for a September screening at Trinity Heights in Sioux City, Iowa, made clear, politics, faith and commerce come together in these outings: “Newt and Callista will be available after the film for DVD signing and a signing of the book, ‘Rediscovering God in America.’ ”

Gingrich’s critics look askance at this busy intersection of personal and public, new faith and old, tribal politics, Roman practice and American commerce. They question the timing and sincerity of the former speaker’s conversion to Catholicism two years ago, especially in light of the Gingrich’s unspoken but unmistakable “I’m one of you” message in the venues where he shows his film to fellow Catholics, who are a key swing voting bloc.

That’s perhaps especially the case because the candidate, who was born a Lutheran and previously a Baptist, did come to his third faith through his third wife. His second wife, Marianne, whom he left for Callista shortly after Marianne received a diagnosis of multiple sclerosis, has called her ex-husband’s most recent metanoia “hysterical” and said, “It has no meaning.”

Some of Gingrich’s fellow conservatives who are Catholic have worried that his personal history of “double spousal abandonment” reflects poorly on the church as a whole. Others want to know whether his admission to the communion of saints was somehow fast-tracked.

Gingrich’s defenders, however, argue that it’s impossible to understand the 2012 candidate today without looking at his faith — just as Gingrich himself insists it is impossible to understand America without appreciating the central role faith played in the country’s founding.

And even one fellow Catholic who does not hold a high opinion of the way Gingrich entered the church, “through the Catholic he was having an affair with,” said this about seeing the now-presidential candidate at Mass frequently at the Basilica: “He goes faithfully and takes it seriously; some [prominent] people put on a show” and seem engrossed in noticing who’s noticing them. Gingrich “doesn’t.’

At a minimum, the thrice-married Gingrich’s metamorphosis from someone who rarely attended religious services to a zealous promoter of God’s central role in the public square does suggest he’s personally capable of the kind of radical transformation he’s urging on the country as a whole.

Monsignor Walter Rossi, rector of the Basilica of the National Shrine of the Immaculate Conception, who prepared Gingrich to join the Catholic church, described Gingrich’s conversion process as serious, thorough and preceded by years of discernment. “If anyone thinks it was a fly-by-night instruction, it wasn’t,’’ Rossi said. “We made sure we covered everything, and it wasn’t lightweight stuff.”

In an interview at the Basilica, where Gingrich first started attending Mass with Callista years ago, Monsignor Rossi spoke at length about serving as Gingrich’s catechist in hour-long Sunday sessions.

Gingrich did not attend the typical group instruction through Rite of Christian Initiation for Adults, which “is the better process for a host of reasons” including the built-in support of a faith community, Rossi said. But Gingrich “went through an adapted RCIA” program and “is not the only one” who has converted to Catholicism that way at the National Shrine, which is not a parish church and so has no regular program for those interested in joining.

Some years ago, Gingrich started coming to hear Callista sing in the choir, and at choir functions, and began frequently engaging Rossi in theological conversations. Of course, many intellectuals have come to faith the way they do everything else, thinking their way in the door. “Because the speaker has a great mind,” Rossi said, he was particularly drawn to Saint Bonaventure, whose work sought to integrate faith and reason. He also gravitated to Thomas Aquinas, who gave us the (not very capitalistic) theory of just price, not to mention the construct of venial and mortal sin, and Saint Augustine, whose just war theory is still as relevant to Catholics as the Constitution is to Americans.

Like all converts, Gingrich learned about the Mass, the sacraments and the doctrine. But the reading list Rossi gave Gingrich was not an easy lift; one text was “Introduction to Christianity,” written by Pope Benedict when as Cardinal Ratzinger he was John Paul’s theologian. Often, Gingrich and Rossi reviewed documents written by John Paul.

“We also brought in people to meet with him,’’ Rossi said, though he declined to elaborate.

Gingrich recently told The Washington Post that in one sense, it was the music made by his wife’s choir that had drawn him into the church — and if that is the case, that isn’t so unusual, either. In the sociologist and novelist Andrew Greeley’s 1990 book “The Catholic Myth: The Behaviors and Beliefs of American Catholics,” Greeley writes that a great many Catholics stay in the church in part for the poetry and the music of Catholicism, both real and metaphorical.

Prayer also played a role, and at some point over the course of his instruction, Gingrich began to pray the rosary: “Between his wife and I, we taught him,” Rossi said.

In an April essay in the National Catholic Register, “Why I Became a Catholic,” Gingrich says yet another influence was George Weigel’s work, especially “The Cube and the Cathedral,” about the scourge of European secularism. But over a three-hour dinner at Taverna Giulia near the Vatican several years ago, Weigel says Newt and Callista Gingrich spoke with him almost exclusively about the subject of another of Weigel’s books, John Paul II. “He was genuinely moved by John Paul and his ability to ignite a ‘revolution of conscience,’ ” in his native Poland, which became the theme of his film.

Gingrich wrote that it was a glimpse of John Paul’s successor, Pope Benedict, during the pontiff’s 2008 visit to Washington that sealed the deal and made him decide to join the church: “I was struck by the happiness and peacefuness he exuded.”

“That was the push he needed to pursue conversion,” Rossi said.

One aspect of Gingrich’s journey that Rossi will not discuss is whether one or both of Gingrich’s previous marriages were annulled; though Gingrich’s second wife, Marianne Gingrich, told Esquire last year, “I got a notice that they wanted to nullify my marriage,” it’s not clear that a second marriage would have been recognized by the church in the first place under canon law.

“His [current] marriage is valid,’’ Rossi said, “so everything else is okay.”

In an interview with The Post’s Karen Tumulty in December of 1994, Gingrich noted that President Lincoln, too, had frequently been asked to explain why he rarely went to church. He quoted Lincoln as saying, “I will rely on those who know me to decide whether or not in fact I seek God’s favor and I fear God’s wrath.” Then Gingrich added, “Lincoln had it right that we’ve drifted into some weird standard, made frankly more by the media than with the public, that I think is not sustainable by normal humans.’’

But the 2012 Gingrich speaks often about his faith’s influence on his politics. In one presidential debate, on foreign policy, Gingrich cited John Paul II as among those who had influenced his thinking on U.S. policy on Iran. In late November, at a Christian candidate forum in Iowa, Gingrich said that although he is not an alcoholic, the principles of Alcoholics Anonymous had helped him turn his life around.

The former Georgia congressman left public life in 1999 after being sanctioned and fined by the House ethics committee in a Congress that was not only controlled by Republicans, but by him personally. At some unspecified point after that, he said in the Iowa forum, “I wasn’t drinking, but I had precisely the symptoms of somebody who was collapsing from under its weight. My life was full of accomplishments and achievements,” but “there was part of me that was truly hollow. I had to recognize how limited I was and how much I had to depend on the spiritual.”

In some of his most Catholic moments to date on the campaign trail, Gingrich initially suggested he supports an expansive immigration policy, which is very much in keeping with the church, but not so in line with the 2012 Republican primary electorate. (He later walked this stance back slightly).

On the abortion issue, the former speaker on one occasion said he thinks life begins at implantation. But after a general outcry among orthodox Catholics, Gingrich amended that, too, and “clarified,” that no, he really believes life begins at fertilization.

Gingrich is one of a number of prominent conservative converts to Catholicism. Others include Kansas Gov. Sam Brownback, Randall Terry, Louisiana Gov. Bobby Jindal and Jeb Bush. Yet of course, each one’s angle of entry and eventual destination is different. For now, maybe the clearest answer to the question of what kind of Catholic Gingrich is is that he is a young one, still learning about his new faith; after only two years, it could hardly be otherwise.