Whether Mormon, Catholic or Protestant, faith a major theme in Rubio memoir

Over the course of his life, Marco Rubio has prayed in Mormon sanctuaries, Catholic cathedrals and Protestant worship centers. But through each denominational transition, faith has remained a driving force through much of the young Florida senator's life.

From the opening pages of Rubio's new memoir, An American Son, to the final sentence, an ongoing theme of Christian faith runs throughout the volume.

Rubio writes extensively in the book, which goes on sale Tuesday, about his devotion to faith, which he has experienced through a variety of traditions: A born Catholic who spent his childhood in Nevada attending services at the local Mormon Church, he convinced his family to return to the Catholic Church as an adolescent. After he married Jeanette Dousdebes, Rubio joined a Southern Baptist congregation and currently splits his time between the Protestant church and Catholic Mass.

Rubio's fascination with religion began as a young child. When his father moved the family to Las Vegas when young Marco was in the third grade, the Church of Jesus Christ of Latter Day Saints (LDS) offered programs and a sense of community that the Rubio's -- a family far from the Cuban exile community they left in Florida -- embraced. According Rubio's book, which is the first time he has addressed his Mormon story at such great length, he dived headfirst into Mormon theology, and despite his age, was the faith leader in his family.

"I immersed myself in LDS theology," Rubio writes, more than 30 years later. "I studied church literature and other sources of information to learn all I could about the church's teachings."

While his parents indulged him, his father "never really embraced Mormonism." A bartender by trade, Mario Rubio had struggled with abiding by the prohibitions against alcohol, tobacco and caffeine.

"[W]hile the church didn't object to one of its members working in that occupation, it considered liquor poison, which could have bothered my father with feelings of remorse for making a living by dispensing it," Rubio writes." It certainly bothered me, and I admonished him for trading in the sinful substance, urging him to find other work. He ignored my tactlessness."

Rubio's grandfather was even more antagonistic. After attending a service, Papa, as Rubio affectionately called him, said "he would never go back because he hadn't seen a single African American in attendance." (Rubio said there was in fact a biracial family who attended the church.) But Papa kept his word, Rubio writes.

Rubio's time as a Mormon, however, was short lived: In 1983, still before his teenage years, he urged his family to return to the Catholic Church. "We left the Mormon Church with nothing but admiration for the place that had been our first spiritual home in Las Vegas, and had been so generous to us," he writes. "I still feel that way."

According to the book, Rubio put forth the same energy he directed to the LDS teachings to the traditions of the Catholic Church, and still considers himself a member of the Church to this day. As a young man, he attended services with his wife at Christ Fellowship Church in Miami, but never felt the same attachment that he did to the ancient church. After years worshiping in a Protestant congregation, Rubio says, a campaign supporter brought him back to Catholicism.

"I love Christ Fellowship--I still do," Rubio writes. "And yet, despite the power of its message, I could never shake the feeling that for me something was missing. ... A deep, almost mysterious, emotional attachment pulled me back to my church. ... But I knew I faced a dilemma."

Rubio's four children now attend Catholic CCD classes and take Communion.

His book suggests that for him, worship does not end when he leaves the church property. Interwoven in the pages of his memoir, in which he takes the reader on a tour of his entire political life, Rubio invokes God in some form almost every step of the way. Early in his career, Rubio avoided discussing his faith because he "had been conditioned by political correctness," but appears to have become more comfortable discussing his spiritual journey in public forums.

The major turning point, he writes, came on his final day as speaker of the Florida House, where he delivered a speech heavy on the role of God on his public life.

"It had taken me too long," he recalls, "but I was determined not to leave the house without paying public tribute to God[.]"

In the book, Rubio devotes an entire chapter to his return to Catholicism, and not unlike a portion of President Barack Obama's political memoir The Audacity of Hope, describes the tenets that drive his faith. Bible verses are strewn throughout Rubio's book, and he describes pivotal instances in his career when he says spiritual guidance helped him gain personal inspiration and strength to carry on.

While campaigning for Senate against former Florida Gov. Charlie Crist and former Rep. Kendrick Meek in 2010, Rubio carried with him a key chain bearing Joshua 1:9 from the Old Testament, which reads in part, "the Lord your God is with you wherever you go."

All of this is part of a common theme that carries on to the final line.

"And last but most important," Rubio begins the final sentence of acknowledgements to friends and family, "I thank my Lord, Jesus Christ, whose willingness to suffer and die for my sins will allow me to enjoy eternal life."