The five things you need to know about Rick Warren

By Daniel Burke, CNN Belief Blog Co-editor

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(CNN) - Best-selling author and megachurch pastor Rick Warren is one of the country's most influential Christian leaders.

But Warren and his wife, Kay, have nearly disappeared from public view since their son's suicide in April.

That changed Tuesday night, when Rick and Kay Warren spoke with CNN's Piers Morgan about the death of their son, how their faith has changed and their new mission in life.

Here are five things to know about the Warrens.

1. They lead the sixth largest church in the United States. 

Since its first public service on Easter in 1980, the Warrens' Saddleback Church has spread to eight campuses in Southern California - as well as four international satellites - and counts some 20,000 weekly worshippers.

That's makes it the sixth-largest in the United States, according to an annual tally kept by LifeWay Research, a Christian firm based in Nashville.

MORE ON CNN: Rick Warren speaks about his son's suicide

2. Warren's book, "The Purpose Driven Life," has sold more than 32 million copies and been translated into more than 50 languages. 

Published in 1992, Warren's spiritual self-help book has topped all four major best-seller lists, according to Warren's spokesman, making it one of the best-selling hardcover books in recent history.

The book reached national prominence in 2005, when hostage Ashley Smith convinced her captor to read portions of "Purpose Driven," after which he let her go.

"That really made Warren a household name," said Jeffery Sheler, author of the 2009 biography, "Prophet of Purpose: The Life of Rick Warren."

By 2005, nearly a quarter of Americans had read "The Purpose Driven Life," Christian researcher David Kinnaman told CNN last year. 

3. Warren is an evangelical.  

That means he falls on the conservative end of the spectrum, theologically.

Like other evangelicals, Warren believes he has a personal relationship with God, that Jesus is the only route to salvation, that the Bible is the inerrant word of God and that he has a duty to spread the gospel.

Warren also falls in line with most evangelical political beliefs, opposing same-sex marriage and abortion, for example. But he and Kay also encourage Christians to care about a broad range of causes, from fighting poverty to global warming.

4. Warren delivered the invocation at President Barack Obama's first inaugural. 

Obama took a lot of criticism for inviting Warren to pray at his first inaugural, mainly because Warren had encouraged his huge flock the year before to support Proposition 8, which outlawed same-sex marriage in California.

But Obama defended his selection of Warren, saying that "part of the magic of this country is that we are diverse and noisy and opinionated."

For what it's worth, Warren has also caught flak for inviting Obama to Saddleback Church, over the objections of conservative evangelicals.

5. Rick and Kay Warren are extremely active in lots of social justice causes.

AIDS, poverty,  gun control - it may actually be shorter to list causes that the Warrens have not dedicated time and energy to.

In 2005, Warren started traveling to Rwanda after an invitation from President Paul Kagame to help make the African nation become the first "purpose-driven country."

The pastor continues to visit Rwanda, preaching a message of reconciliation nearly a decade after the country's devastating genocide.

After his son's death, Warren has preached about using his pain and sorrow in service of others. He and Kay also say they have a new mission: shedding light on the toll of mental illness in the United States.

MORE ON CNN: Rick Warren returns to the spotlight