The concept of Satan provokes strong emotions, and sparks a series of fundamental questions about good and evil, about human nature, and about the nature of God.
The question of whether Satan exists is one of the most contentious theological debates possible, and last week four fascinating, polarizing people from around the country convened in Seattle to tackle that topic in the third "Nightline" Face-Off.
According to one poll, 70 percent of Americans believe Satan is real. Some believe he -- and almost all believers say Satan is a "he" -- is a fallen angel. Others believe Satan is a shapeless, malevolent force; the enemy of God. But there are also many people who believe that Satan is a myth, and a dangerous one, because his name is often invoked to justify unspeakable acts of violence.
The Face-Off was hosted at Mars Hill Church, and the church's pastor, Mark Driscoll, argued that Satan does exist. Driscoll is a hip yet hard-line preacher with a young, often tattooed following to whom he preaches a strict doctrine, in which the devil figures prominently.
"It could get intense," Driscoll said of the debate. "It could get passionate. But as long as it doesn't become personal then I think it's OK."
Driscoll's teammate for the evening was Annie Lobert, who arrived in Seattle from her home in Las Vegas -- otherwise known as Sin City.
"I don't have a theologian background, but I have 16 years of experience of walking with the Devil so I know he's real for sure," she said.
Lobert is a former prostitute who says she used to see the Devil in the eyes of her johns. Her organization, Hookers for Jesus, ministers to sex workers.
"When people don't believe the devil is real, I feel, my opinion is, they are deceived," she said.
Lobert felt she could "definitely" change minds by "talking from the heart, from experience."
On the other side of the debate was Bishop Carlton Pearson, a former fundamentalist preacher who says he used to cast demons out of his followers.
"What's interesting about this thing tonight is that I've been on both sides," he said. "I was a staunch 'believe it my way or go to hell' kind of preacher for the first half of my life. And I never liked it."
After watching a video of the Rwandan genocide, Pearson said he realized all those people would not be going to hell just because they weren't saved. He declared he no longer believed in the devil or hell, and was called a heretic and lost his church.
He said his views are seen in the evangelical community as "treasonous is some ways. It breaks people's hearts."
Arguing alongside bishop was Dr. Deepak Chopra, a physician and best-selling author of dozens of books and videos on health and spirituality.
"My position is that we have a huge problem with what people call evil in the world and they need a good rational explanation and not an irrational mythical explanation," he said.
"I am not going to do anything to offend [the other side]," he said. But I still have to speak my own truth."
At the church, volunteers and security guards prepared for a crowd of more than a thousand people.
"Nobody in the Bible talks about hell or Satan more than Jesus," said audience member Mike Garcia. "If Jesus talks about Satan and the reality of hell, then it has to be true."