(CNN) – 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.

Tune it to CNN's documentary "Romney Revealed: Family, Faith and the Road to Power," with Chief Political Analyst Gloria Borger, debuting Sunday night at 8 p.m. ET on CNN.