The Nightline Face-Off

May 2, 2007 — -- Why are Kirk Cameron, a preacher, and two self-proclaimed atheists coming together in a church this weekend? Because Cameron and preacher Ray Comfort claim that they "can prove the existence of God."

They'll take on the atheists in the first "Nightline Face-Off," a debate to be moderated by "Nightline" anchor Martin Bashir.

Watch the Face-Off Wednesday May 9 at 2 p.m. on ABC News Now, and on Nightline at 11:35 p.m.

As Mike Seaver, the oldest son in the smash hit sitcom "Growing Pains," actor Kirk Cameron could make audiences roll with laughter. But now he wants to bring them to the Lord. And he's deadly serious.

In March 2006, "Nightline" profiled the Way of the Master, a Christian ministry headed by Cameron and itinerant preacher Ray Comfort. Operating as a charitable trust, its intention is to educate and equip the church to preach the message of Christianity to nonbelievers. Cameron says he is motivated by a literal fear of hell.

"I believe the Scriptures teach that there's a literal heaven and a literal hell, just like Jesus said," he explained. "And without forgiveness of sins that, yeah, the place of punishment is called hell."

The Way of the Master has a weekly television show for which Comfort and Cameron literally hit the streets in the name of Jesus, challenging nonbelievers that their sins against God will lead directly to hell.

"On the Day of Judgment," Comfort tells one man on the streets of New York, "God will see you as a lying, thieving, blasphemous, adulterer at heart. You have sinned against God. You need his forgiveness."

On occasions, things go badly wrong and the pair are attacked by members of the public. Comfort recalled one incident, saying, "While I was preaching the Gospel a gentleman came up and he started spitting on me. And he spat quite a few times." Comfort says he simply remained calm and moved on.

Neither Comfort nor Cameron has theological degrees nor any kind of formal training. But Cameron says he's convinced his new career is vitally important.

"I have no authority. I am simply trying to be faithful to the God who saved me, who changed me and who has commissioned me to tell you and those who are watching this interview … about the Gospel of Jesus Christ and that it has the power to change people's hearts."

"There isn't any good reason to believe in God," so says Brian Sapient, a member of the Rational Response Squad, a group of atheists "Nightline" profiled in January.