Sen. Rand Paul (R-Ky.) speaks during a rally to formally announce his presidential campaign at the Galt House hotel in Louisville on Tuesday. (Daniel Acker/Bloomberg)

Sen. Rand Paul, a libertarian who has pitched himself to social conservatives, became the second Republican to launch his campaign Tuesday in Louisville.

Paul was baptized into the Episcopal Church, but he has been a member of the Presbyterian Church in Bowling Green, Ky., which is part of the Presbyterian Church (U.S.A.). “Rand and Kelley are both devout Christians and are active in their local church,” his new Web site’s bio reads.

“My faith has never been easy for me,” Paul said when he spoke in 2012 at the Family Research Council’s Values Voter Summit — an annual social conservative gathering. “Never been easy to talk about and never been without obstacles.”

Paul told the crowd that he struggled to understand “how tragedy could occur in a world that has purpose and design,” saying he does not wear his religion “on my sleeve.”

[A brief guide to what Rand Paul actually believes]

In an interview on the religious broadcasting station Daystar, Paul suggested that his faith didn’t always stick.

“As a teenager, I found that something was missing and decided that I would find that in Jesus. It’s something that – I tell people it didn’t always stick, either. I don’t know if that’s not – if that’s uh, blasphemy to say you have to be saved more than once, but I think sometimes it takes more than once for people.”

Paul cited his work in medicine as something that presents tensions in his faith.

“I’m also somebody who’s in science and medicine, so it’s not always been easy for me to say, well, gosh, how do I see God’s hand in this horrible, horrible thing that I’m seeing, how do I see God’s presence in something – you see small children dying from brain tumors and this and that,” he said. “Religion and faith isn’t always easy. But I always keep coming back.”

Paul did not get off to a smooth start with at least one evangelical leader. In 2010, when Paul was first running for U.S. Senate, Focus on the Family founder James Dobson switched his endorsement from Trey Grayson to Paul in the Republican primary.

Dobson said that “senior members of the GOP” mislead him by saying that Paul was pro-choice. He said that Paul identifies with the tea party and calls him “my kind of man.”

During that same race, Paul later chastised his Democratic opponent for an ad referencing Paul’s time as a student at Baylor University. Paul attended Baylor but his MCAT scores were high enough that Duke accepted him into its medical school without an undergraduate degree.

The Democratic candidate’s ad referenced stories about Paul’s past. “Why was Rand Paul a member of a secret society that called the Holy Bible a ‘hoax’?” the ad’s narrator asked. “Why did Rand Paul once tie a woman up, tell her to bow down before a false idol and say his god was ‘Aqua Buddha.’ “

Paul denied involvement in a kidnapping, saying that he went along with a college prank. He was a member of a secret society at Baylor that would mock Baptist culture, something that came under the spotlight during his Senate run.

Paul’s wife, a deacon at their church, said she was shocked by the religious attack of his opponent. “Rand and I are both Christians and our faith is very important to us,” she said at the time.

Want more news on religion? Read more from Acts of Faith:

Here’s what we know about the faith of Sen. Cruz, who’s set to announce his 2016 bid at Liberty University

Here’s why Liberty University has become a pilgrimage site for GOP candidates

How will evangelicals vote? What Ted Cruz’s announcement means for his rivals.