With Bible verses painted on the walls of his living room and with an unshakable belief that hell is for real, there's no question that Rob Seyler is a devout evangelical Christian.

He is also a renegade.

Tucked into his well-thumbed Bible, the spine held together with silver duct tape, is a picture of Marilyn Manson in full goth makeup. Seyler, a high school Bible teacher, says the metal singer's writings shed light into the secret world of suffering teens.

Musically, Seyler gravitates more to Johnny Cash, partly because of the musician's intense religiosity. But Seyler will be the first to tell you that Cash's memoir of life as a sinner, "Man in Black," is much better than Cash's Christian novel, "Man in White."

His renegade streak extends to Seyler's classroom at the Grandview Park Baptist School in gritty East Des Moines, where he has painted so many brightly colored quotes and pictures onto the walls that it looks like a pop artist's studio. There are Bible verses and a black and white silhouette of Johnny Cash and an image that Seyler says has "created a little bit of a ruckus."

It's a portrait of Barack Obama.

Students aren't the only ones who have questioned Seyler's depiction of a politician who supports abortion rights and gay marriage on the walls of a conservative Baptist school.

The senior pastor at Grandview Park Baptist Church -- which anchors Seyler's school and where Seyler and his family are members -- doesn't much care for it, either.

"When I first saw that on Rob's wall, I thought, 'What's the point?' " says the pastor, Robert Smith. "I don't know where Obama is as a Christian."

Seyler used to wonder about that, too. But after reading the president's speeches and writings about his faith, including his acceptance of Jesus, the teacher concluded that Obama was an eloquent spokesman for Christian salvation. So he painted the president onto the front wall of his classroom.

"I wanted to put the kibosh on negative comments about Obama," says Seyler, 38, sitting on a desk a few feet from the smiling, arms-folded Obama silhouette he painted in 2008. He also wanted to remind his students that submitting to government authority is a biblical mandate, whether that government is led by a Republican or a Democrat. Painted on Obama's chest are the words "Romans 13:1," a New Testament verse that commands Christians to obey government authorities.

To be sure, Seyler is no fan of Obama's policies. The father of six has been uncompromisingly anti-abortion since seeing videos of abortion procedures at the Christian high school he graduated from in Pennsylvania. And he believes gay marriage is an insult to a divinely ordained institution.

Yet Seyler, who has always supported Republicans for president, cringes at the thought of having to paint over Obama with a portrait of Mitt Romney. How could a teacher whose mission is instilling orthodox Christianity in the hearts and minds of impressionable teenagers justify a portrait of a Mormon at the front of his class?

As certain as he is that Obama is Christian, he's sure that Mormons are not.

"Not to shun Mormons, but they teach that Jesus was a man exactly like you or me and that men can become gods," says Seyler, whose completely shaved head and bushy rust-brown goatee give him the air of a biker dude.

It's those kind of teachings, he believes, that can land you in hell.

So even though nearly everyone in Seyler's close-knit extended family has fallen into line behind Republican nominee Romney -- "he's the lesser of two evils," his brother-in-law Chris explains over burgers out one night -- Seyler isn't sure he's going to cast a ballot for president this year.

He might stay home instead.

Plenty of congregants at Grandview Park Baptist Church face the same predicament: Is it better to vote for a Mormon or to not vote at all? "It's a conundrum," says Smith, the senior pastor, who is personally keen on Romney. "It's tough for a lot of people."

In a close election that hinges on turnout, as might happen this year, that fact could spell deep trouble for the Republican candidate, especially in a swing state like Iowa.

Voters like Seyler who can't countenance Romney's Mormonism represent "a small but potentially crucial set of evangelicals," says John Green, an expert on religion and politics at the University of Akron. "If we get to the point where every vote counts, then a 5 or 10 percent decline in evangelical turnout can make the difference."

So a key part of Romney's job over the coming weeks is convincing the Rob Seylers of the world that, yes, it's better to support a Mormon than to stay home on November 6.

But Seyler's not there. Not yet.

"We have traditionally been a Christian nation, and God has blessed us because of that," he says. "And now we're going to hand the reins over to a Mormon?"

Rob Seyler spends a lot of time talking about eternity.

His classroom is hung with plastic human skulls and skeletons (he took one down after feeling the place might be getting too morbid), and a wooden coffin stands in a rear corner. A student once hid inside it, emerging when class was well under way to scare his teacher and classmates half to death.

"Teenagers are convinced that they're immortal and invincible," Seyler says, explaining the ghoulish kitsch. "I want to remind them that life is short."

And that eternity is long.

Seyler illustrates just how long with a ball of blue yarn.

It's a sunny Sunday morning in early August, and he is standing in front of 20 kids in a different classroom, leading a Sunday school class for Grandview Park Baptist Church.

Seyler asks for volunteers, and a grove of eager hands shoots up. A boy with an Afro is soon following Seyler's instructions to pull one end of the yarn to a corner of the room. Seyler asks another kid to pull the yarn to the next corner, forming a giant L.

Before long, all the children are up from their seats and stationed around the edges of the room, each doing his or her part to form a rectangle of blue string about 100 feet long.

When the yarn is completely unspooled, Seyler holds up his end, wrapped in an inch of white athletic tape.

He explains to a room of first- through fifth-graders that this short length of taped string represents a human lifespan on Earth, while the rest represents the time we spend in eternity, after death.

"When we die, we go to heaven or hell," Seyler tells them. "We have a lot more to live after we die, but lots of people just focus on this little piece."

The only way to get to heaven, he continues, is to accept Jesus as savior, to recognize that he took on our sins and died for them: "I love Jesus more than my own life; that's how tight we are."

"I love Jesus more than my own kids," he says a moment later, catching the eye of his 9-year-old, Jack, who is seated in the front row.

None of Seyler's teachings about eternity or hell comes even close to resembling a political statement. Yet they go a long way in explaining how a born-again Christian could have such deep reservations about a Mormon candidate.

In Seyler's view, getting it right when it comes to God and Jesus is a high-stakes business, the difference between spending eternity in heaven vs. hell. So why would he trust the country with someone whose beliefs are shaped not just by the Bible but also by another text, the Book of Mormon?

Never mind that Mormons consider themselves Christians and focus intensely on Jesus, starting with the official name of their church: the Church of Jesus Christ of Latter-day Saints. For Seyler, that just makes a Romney presidency even more dangerous.