Story highlights Mitt Romney's missionary service in France as a teenager changed his life

He was thought to be dead after a tragic car accident that killed a passenger

As a church leader in Massachusetts, his role "was like the pastor"

Wife Ann Romney's diagnosis in 1998 of multiple sclerosis also strengthened their bond

It is a side of Mitt Romney the public often does not see -- opening up about his faith, devotion to his family and his work as a Mormon overseas missionary and later church leader at home.

In a rare discussion of these topics, he described to CNN Chief Political Analyst Gloria Borger his 2½ years as a teenager serving as a church missionary in France. He said that period helped "ground my relationship with God" and cement his beliefs.

When Romney sat down with Borger this summer for CNN's documentary "Romney Revealed: Family, Faith and the Road to Power," it was while he was campaigning and fundraising in Indiana -- and just a day before he secretly met with Rep. Paul Ryan to offer him the No.2 slot on the Republican ticket.

While it might be expected Romney would be guarded and on message as he is usually is on the campaign trail, he was candid on a range of topics -- from his private life to religion to his wife -- areas he rarely has talked about.

As he prepares to accept his party's nomination for president, Romney and his team are trying to show the voting public a more personal side of the candidate.

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On a mission in France

Describing his mission in France, he talked about how he would walk the streets of Bordeaux up to 60 hours a week trying to convince people why they should convert -- in French. Often he would have doors slammed in his face.

"When you're off in a foreign place and you only talk to your parents once or twice a year by phone -- that's all that's allowed -- and you're out speaking to people day in and day out about your faith and your religion and differences between your faith and other faiths... you say, 'OK, what's important here? What do I believe? What's truth? Is there a God? Is Jesus Christ the son of God?'" he told Borger.

"These are questions that are no longer academic. They're critical because you're talking about that day in and day out. And so I read scripture with much more interest and concern and sought to draw closer to God through my own prayer. And these things drew me closer to the eternal and convinced me that in fact there is a God. Jesus Christ is the son of God and my savior, and these are things that continue to be important in my life, of course."

Left for dead

What many people don't know is that during this time he was involved in a car accident as he was driving the mission president and his wife during a six-hour ride between Paris and the south of France. Their car was hit by what was believed to be a drunken driver. The mission president had to return to the United States because of his injuries, and his wife was killed.

Initially Romney was pronounced dead. He told CNN this was a time of "challenge and soul searching."

"The person sitting next to me died, and others were severely injured. My injuries were not as severe as some might have thought. The policeman on the scene apparently thought I was in worse condition than I was and wrote, in French, 'he is dead' on my passport to distinguish me from others. That made it back to the United States in a press report that I had been killed in an accident. My parents heard it through the media, as did Ann," he said in the interview.

Romney, who was the president's assistant, was left to help lead the mission, and under his watch the number of converts went up.

Back in Boston

After he and Ann were married and they later settled in Boston, Romney became a church leader there. He would serve as head of the Belmont, Massachusetts, congregation and his duties included not only leading the service but also counseling people, comforting the sick and arranging financial help for those in need.

"It's an unusual part of my faith in that we don't have a full-time ministry. There's no one paid to be the pastor and conduct services on Sunday and really no one who is full-time with the church to care for the sick and visit the poor. And so the church comes and says, 'We'd like you to do that, Mitt.' And so for about 10 years I took responsibility for the congregation or a group of congregations, and in that regard I was like the pastor."

This work and his later job of leading all of the Boston congregations will likely be highlighted during the Republican convention this week, in an attempt to show a more personal side of the nominee-to-be.

"Talk about a growing-up experience and a learning experience. You try your very best to align yourself with the Almighty and what God might say, and of course you look to get direction from the church as well," he told Borger.

Romney and the role of women

His tenure was not without controversy. Some women in the congregation have complained he did not do enough to give women a more prominent role in church activities. He said he worked hard to make the church inclusive.

He also described Ann's diagnosis, in 1998, of multiple sclerosis, a disease that can shut down the nervous system. Family members and friends said that was a moment that rocked the family because Ann was known as the stabilizer of the family.

He talked about the time when the couple went to the neurologist after Ann started having serious problems -- not knowing if the cause would be fatal.

"It was very clear that she was flunking the examination. She couldn't stand on her right foot without falling over and things like that. (The doctor) stepped out and she began to cry and I welled up tears as well and we hugged each other, and she said, "Something is terribly wrong," and I said, "Yes, but Ann, we can go through anything so long as it's not fatal."

"For me, I love Ann," he continued, "not because she can cook and not because she can fix things around the house. I love Ann because of who she is. And for me, as long as she was able to be alive, our life would be fine."

So with one of the couple's five sons still at home, Romney started doing the household chores, picking up food at the grocery store and doing whatever was necessary.

"She battled through it. She got good help from wonderful physicians and over the course of all the care she got she was able to stop the disease in its tracks. It's relapsing and remitting in her case. It's stopped and she's been pretty solid ever since. But whether it has or not, just having her around makes my life complete."

In a separate and emotional wide-ranging interview, Ann Romney described to Borger how the illness completely frightened her and how supportive her husband was.

"Even when I was as sick as that he would curl up in the bed with me," she said. "It was like he was gonna do anything he could do just to say I'm here. You're OK. Just stay right there, and we'll be OK."