It's been more than two decades since Kirk Cameron, the teen heartthrob, became Kirk Cameron, the Christian actor.

Cameron's conversion changed how he famously played Mike Seaver on Growing Pains and altered the path of his career, leading him to roles in faith-based films such as Left Behind and Fireproof, and his Christian TV program, The Way of the Master.

During his 20-some years as a believer, evangelicalism in America has grown more politicized and skeptics have grown more vocal.

Cameron, who will be speaking in Houston on Oct. 1, now finds himself called to point the country back to its Christian roots. This month, he finished filming Monumental, a documentary that tracks God's influence on the formation of America.

"There's something in the soul of America that seems to be getting sicker," Cameron said. "I'm retracing the footsteps of our founders from England to America in the hope of rediscovering our true national treasure so that we can use it to restore our country."

The role of God in history — or "His story," as Cameron says - has long been a topic discussed by religion scholars and some evangelical groups. It's becoming more prominent, tied in with current political issues at events such as the Values Voters Summit, held by the Family Research Council, and Glenn Beck's Divine Destiny, which took place in Washington last month.

"The sort of thing he's trying to do will resonate with a pretty large segment of the evangelical population, but there's also criticism from people who are pretty reticent" over the idea of God's favor on America in particular, said Larry Eskridge, associate director of the Institute for the Study of American Evangelicals at Wheaton College.

"Over the last 20 years, particularly with the growing political dimension of the evangelical movement, that has kind of been a spark point," he said.

Cameron didn't participate in Beck's event. Like several other evangelical leaders, he voiced concerns over Beck's Mormonism but said he supports his efforts.

"When I see Glenn Beck or whoever - be they a Jew, Mormon, Catholic, anyone - saying we need to wake up because socialism is hurting our country, the economy is suffering, I think that's a good thing," Cameron said. "My trust is not in Glenn Beck, it's not in my personal heroes of the faith, it's in an almighty God who will work to bring about good," even by using Beck.

Cameron remains one of the most prominent - and outspoken - Christians in Hollywood. His involvement in ministry makes him a symbol of contemporary Christianity, both for the segment of evangelicals who will fill theaters to see his films and for the skeptics ready to laugh at his assertions of faith.

A clip from his show The Way of the Master in which Cameron listens to co-host Ray Cutler argue that the design of a banana is evidence of creation over evolution has become a viral YouTube video and Internet meme.

"I can fully relate to mocking Christians; I used to do it myself before I came to Christ," Cameron said in response. "I used to think I was too smart to believe in God and be a Christian, but the more I've looked into and studied it and researched, the evidence is clear on the side of there being a God and Christ being that God."

Growing levels of unbelief should also encourage them to take the call to evangelize more seriously, but with grace and understanding rather than cockiness and arrogance, he said.

"There wasn't a whole lot of opposition in the first 50, 100 years of our nation's existence. Now, with secular humanism and new militant atheists, you have people trying to make it sound like Christians are a joke … . It's a wake-up call today. It's a call to man-up."

During his Houston visit, Cameron will share his testimony and urge Christians to live out the Great Commission, Christ's call to reach nations with his Gospel. He is speaking at an event for World Hope Ministries, a locally based missions organization.

"Kirk Cameron will really help equip the people so that when they leave they can go out and share the message," said World Hope's president, Pastor Dwight Davis.

It's Cameron's first time getting involved with World Hope, which helps churches organize missions trips and sponsors tens of thousands of missionaries in countries including South Africa, Kenya, Ecuador and Honduras.

"I'm helping to bring some awareness to what they do, which is helping people express the Great Commission as they go out into the world," he said. "Sharing your faith with someone else ranks up there with one of the scariest things a Christian can do. It's kind of silly when we think of the Good News. We need to let the love of God out."

kate.shellnutt@chron.com