Bill and Mary Manseau's marriage has brought them into a decades-long confrontation with the church they love.
From a young age, both were devout Roman Catholics.
As a kid, Bill Manseau said he "used to play Mass … as many Catholic kids do." He would recruit his younger siblings to be altar servers and use Necco wafers for communion. At age 19, he entered the seminary.
At age 17, Mary Manseau entered the convent. "I was a very strong, very loyal, very devout Roman Catholic," she said. "And in those days, whatever the church said, that's the way it was."
Despite their devotion, both Mary and Bill eventually began to question the church. Mary left the convent after only a few years.
At the seminary, Bill came to a radical conclusion: Forced celibacy is wrong -- an invention of the church, not the Bible. "For thousands of years," he said, "there were married Catholic priests, married bishops, married popes." Manseau decided that to be more fully a holy man, he needed to experience the "holy union" of marriage.
Not long after that, he met Mary.
In 1969, the priest and the former nun got married. They went on to have three children.
By the time they wed, Mary was no longer a nun. Bill, however, was still technically a priest, although he was no longer allowed to perform many priestly duties, such as running a parish.
Bill became a crusader for the rights of married priests -- a position that put him at odds with the church hierarchy. The church believes that the commitment of celibacy is an act of love for God and is central to a priest's ability to do his job.
Manseau's conflict with the church entered a new level in 2003, when he decided to ask the church to formally recognize his marriage. In response, he said the church asked him to sign papers that essentially said his ordination was a mistake, "I could not assent to that," he said, "because it's not true."
Even though he now faces a church trial over his marriage, Bill Manseau continues to argue that forced celibacy is at the heart of the priesthood's current problems: poor recruitment and sex abuse scandals.
"You're forcing people to do something which is against their nature," he said. "The priests have been coerced for centuries and look at what the fruit has been -- a lot of destroyed lives, a lot of unhappy lives … and in recent years the revelation that this has been devastating for children."
The Manseau family story is now chronicled in the book "Vows: The Story of a Priest, a Nun and Their Son," written by their middle child, Peter.
(For more information on the book, go here: www.petermanseau.com.)
In preparing to tell their story, the Manseaus decided to reveal an agonizing secret: Mary Manseau had been abused as a teenager … by a priest.
"I was sexually abused," she said. "I never told a soul … and I went through periods of depression always wondering, 'Why, why, why?'"
Despite the distress and the disputes, the Manseaus still want to be part of the church.
"Because I love it," Bill Manseau said. "I will not be driven away from my heritage by people who are nearsighted."
Both say their faith has been tested throughout their ordeal -- but that they now have a new and deeper faith. As Mary Manseau put it: "It's moving from one kind of faith -- of total believing in everything that the church says -- to realizing that that isn't what faith is."
ABC News asked the Archdiocese of Boston for comment on Bill Manseau's case. The communications office provided a written statement, saying, "We do not publicly discuss personnel matters."
The statement went on to say, however, that "celibacy is not simply focused on living with the renunciation of marriage, it is an act of love for God and God's people. The commitment made by a priest to a life of celibacy is centered on deepening the experience of solitude, communion, love and giving life and is fundamental to a priest's ability to sustain his calling."