Just before a Sunday morning service in the early 1990s, two women walked into one of Manhattan’s most venerable sanctuaries, Marble Collegiate Church, on Fifth Avenue. The usher who seated them, sizing them up as first-time worshipers, asked what had brought them to Marble, as the church is known.

“They said, ‘We understand this is where Marla Maples met Donald Trump,’” recalled the choir director and organist at the time, Kevin Walters, “‘so we thought we’d come and see if we could hook up with a billionaire, too.’”

For all that has been written about Mr. Trump’s high-profile careers — as a real estate developer, a casino owner and a reality-television personality — relatively little attention has been focused on the role religion played in shaping his personality. Overlooked amid tabloid accounts of his romances or financial-page articles about his ups and downs are the periods in his life when he was going to church, first as a regular at a Presbyterian church in Queens, where he grew up, and later, as a less frequent worshiper at Marble, one of America’s oldest and most famous churches.