From Jacksonville to Tampa, Florida (CNN) -- If you thought you had less than three perfectly healthy months to live, what would you do? Would you travel? Spend time with loved ones? Appreciate the joy life has given you?

Or would you ditch your kids and grandkids, join strangers in a caravan of RVs and travel the country warning people about the end of the world?

If you're Sheila Jonas, that's exactly what you'd do.

"This is so serious, I can't believe I'm here," says Jonas, who's been on the road since fall. Like her cohorts, she's "in it 'til the end," which she believes is coming in May.

She won't talk about her past because, "There is no other story. ... We are to warn the people. Nothing else matters."

Such faith and concern drove her and nine others, all loyal listeners of the Christian broadcasting ministry Family Radio, to join the radio station's first "Project Caravan" team.

Learn about other doomsdays that have come and gone

They walked away from work, families and communities in places as far-flung as California, Kansas, Utah and New Jersey. Among them are an electrician, a TV satellite dish installer, a former chef, an international IT consultant and a man who had worked with the developmentally disabled.

They gave away cars, pets, music collections and more to relatives, friends and neighbors. Some items they kicked to the curb. In homes that weren't emptied, clothes are still hanging in closets, and dishes, books and furniture -- including one man's antique collection -- are gathering dust. Unless, of course, they've been claimed by others. If you believe it's all going to be over soon, why would it matter if you close the front door, much less lock it, when you walk away?

It's a mid-winter morning in Jacksonville, Florida, when CNN joins this faithful caravan. The "ambassadors," as they call themselves, are easy to spot. They are the 10 people milling about in an RV park drawing stares, eye rolls, under-the-breath mutters and, at times, words of support.

They're wearing sweatshirts and other clothing announcing the "Awesome News," that Judgment Day is coming on May 21. On that day, people who will be saved will be raptured up to heaven. The rest will endure exactly 153 days of death and horror before the world ends on October 21. That message is splashed across their five sleek, vinyl-wrapped RVs, bearing this promise: "The Bible guarantees it!"

Maneuvering onto the road with such a serious statement takes time and patience.

The five vehicles in this caravan are numbered 11 through 15, and the ambassadors line them up in numerical order before hitting the road. They work hard to stay in one lane and keep other cars from breaking into the convoy. That's the best way to be noticed, they say.

The drivers, their vehicles spread out in a parking lot, spend about 10 minutes doing a choreographed RV dance to get in proper formation.

From the back of No. 14, we hold tight to our equipment, and our seats, as the jerking around begins.

Reverse. Forward. Turn to the left.

"Eleven, 15, go back please," a voice crackles over the walkie-talkies.

Spin around. Veer right. Stop. Wait.

"Is everyone in order and ready to come out of there?" Crackle, crackle. "13?"

"Ten-four."

"I hope the Rapture is smoother than this," one driver says.

Since this inaugural caravan team embarked on this doomsday journey, two other teams have set out elsewhere -- one is in Pennsylvania, another in Texas. A fourth and final group will soon follow.

They have been chosen by God to spread the news few understand, the ambassadors say. They liken themselves to biblical figures, including Jonah, who God commanded to warn the people of Nineveh of their city's destruction.

They say their work comes with ample precedence, that the God they believe in would never bring judgment on his people without warning them first. Their job is to "sound the alarm," they say, pointing to Ezekiel 33. Just by being out in their RVs, wearing their T-shirts, jackets and caps, and passing out their pamphlets -- which they call tracts -- they are fulfilling a mission.

The RVs pulled out of the Oakland, California, Family Radio headquarters in late October. The odometers are nearing 30,000 miles as this team, which first traversed the Pacific Northwest before weaving its way through the South, heads toward its next destination: Tampa, Florida.

But avast, ye scurvy readers, this isn't just any time in Tampa. Awaiting the ambassadors are, by some estimates, 400,000 people gathering for the Gasparilla Pirate Fest -- a Mardi Gras, of sorts, for throngs of drunken buccaneers.

Blanketing the world with doom

The ambassadors each remember the first time they heard Family Radio.

Adam Larsen, 32, was a student in Phoenix, Arizona, working nights as a security guard with his Bible already open in front of him. Darryl Keitt, 51, remembers flipping through stations back in 1976, when he might have been sporting his 4-inch platform shoes, looking for disco music.

Team leader Fred Store, 65, was road tripping between Sacramento and Bakersfield, California, when he first tuned in to the station's inspirational music and talk 15 years ago.

John Gallegos, 75, found it five years earlier while driving a truck between Utah and Wyoming. And David Liquori, 45, was so taken when he stumbled upon it 28 years ago that he's gone stretches as long as three years in which he's listened all day, every day.

The voice that grabbed most of them belongs to Harold Camping, host of the program "Open Forum" and the force behind Family Stations Inc., home to Family Radio.

Starting with one station in Oakland, California, in 1959, Camping's Family Radio now boasts 66 stations across the United States. Thanks to strategically placed satellites, shortwave radio and the internet, the message has gone global in 61 languages.

"We pretty much blanket the whole world," says Camping, 89.

This degreed engineer, who calls the Bible his "university," believes the church age ended and the "Great Tribulation" (the years leading up to the end, he says) began on May 21, 1988, when Satan entered the pews. Truth, he says, can be found only in the Bible and not through the mouths of clergy.

He has dissected scripture and crunched his biblical numbers to come up with the fateful dates. He rattles off mathematical explanations of how he did this work, throwing out Bible verses and calculations that leave an outsider's head spinning.

But Camping also happens to be the man who once said September 6, 1994, would be the big day.

He explains now that he originally thought 2011 was the year, but a few verses tripped him up and he concluded that the Great Tribulation might get cut short. There was still scripture he was grappling with, end-time signs that were to come -- he points to the gay pride movement as one of them -- and truths that had yet to be revealed, "but because of the urgency of time I had to get it out quickly," he says of his previous warning.

This time around, he has no doubts.

"I know it's absolutely true, because the Bible is always absolutely true," he says. "If I were not faithful that would mean that I'm a hypocrite."

'Amazing how God works'

Behind the wheel of RV No. 14 is 32-year-old Adam Larsen, the youngest ambassador on this caravan team.

Larsen hands around his smartphone to share YouTube videos, including one showing billboards around the world proclaiming the May doomsday warning. Next he pulls out what looks like a glossy business card, one he says he likes to lodge in gas pump credit card slots so people are forced to see it. The card reads: "He is coming again! May 21, 2011."

Spreading this message alongside like-minded people is of great comfort to Larsen. Back home in Ellsworth, Kansas, he walked this end-time walk alone and didn't feel heard. The opportunity to focus full-time on what he believes, to serve God as a "moving billboard" in his RV, was one this avid hunter couldn't ignore.

"My favorite pastime is coon hunting," he says, referring to the raccoons he targets in rural Kansas. "I had to give that up, but this is far more important."

Much like the animals on Noah's ark, these ambassadors generally travel in pairs. Larsen's RV partner is Keitt, the former disco fan, of Elizabeth, New Jersey. He seems the most comfortable of the ambassadors talking to outsiders and doesn't incessantly quote scripture like others do. After he mentions that he's on a diet, he gets the humor when asked, "What's the point?"

When prodded to discuss their "bucket lists," most caravan members find the question absurd and dismiss it immediately. There's nothing they'd rather be doing now. But Keitt at least admits he would have liked to have gotten married before the world ended.

He'd been a seeker, someone who began looking for God and truth as a teen. He has family roots in a Pentecostal denomination, went to a Catholic school and has dabbled in everything from astrology and metaphysics to Eastern religions. His mother and brother converted to Islam.

Unlike some of the others, he says, he's lucky to have the ongoing love and support of his family, even though, "I'm sure, in the back of their minds, they're hoping I'll come to my senses."

His current beliefs evolved gradually and became solidified about a year ago after he lost his job in social services, rebounded from a DUI arrest after a car wreck and found himself with the time -- and the need -- to study, pray and really listen to Family Radio.

"It's amazing how God works," he says. "You can be at your worst, and he'll lift you up."

Warning, not saving

The ambassadors stream into a Waffle House, one of their favorite Southern discoveries, for lunch before arriving in Tampa.

After bowing his head in prayer and biting into his BLT, Liquori, a loyal Family Radio listener from Long Island, New York, begins to offer glimpses into what he left behind.

Separated on and off from his wife for eight years, he texts with his 12-year-old son daily. He hopes the boy's mother will send the boy for a visit before it's all over. His family doesn't appreciate what he knows, he says. His father is a lapsed Catholic, his mother is Jewish -- he calls Judaism a "dead religion" -- and his brother is either an atheist or agnostic. He isn't sure.

But what he does know is that he feels closer to his fellow travelers than he does his family.

"We can only have intimate relationships with other children of God," he says.

Across from him sits Gallegos, from Utah -- at 75 the team's oldest member. While most all the ambassadors on this trip are single, divorced or separated, he is an exception.

He's left behind a wife of 53 years, a woman he says he was betrothed to at age 4. She shares his beliefs, he says, but wasn't up for hitting the road by RV. He also walked away from his 10 children and their families.

One might think this sort of separation would weigh on a man, but Gallegos says he misses his quality time with God more than his wife. He says he used to study scripture and engage in prayer 10 hours a day. Now Gallegos steals moments each morning with his heavily highlighted and tabbed Bible, and he reads verses to the group when they gather in circles for prayer.

He and the other caravan members say they may be the chosen ones to lead this charge, but they don't fight alone. With announcements made on Family Radio of their impending arrival in new cities, local listeners -- about 30 of them in Jacksonville, dozens of others in Tampa -- get in on the gospel action, too.

Part of that work is answering the challenge they hear most from Christians, who say the Bible teaches them no one can know when Judgment Day is coming.

That may be true, this group says, but as the end approaches the rules have changed. They say secrets God told to Daniel -- as in the Book of Daniel -- have now been unsealed, revealing new truths.

And now that they know what they believe to be true, their job is to warn -- not save -- others.

What a person can do upon hearing the warning remains slightly unclear. They want people to open Bibles and study for themselves. They suggest that everyone "cry for mercy."

But they also believe that before he created the world, God predetermined who will be saved when the Rapture comes. So if you're not part of the elect, the 2% to 3% of the world destined to be saved, what does it matter if you spend the next three months reciting scripture or, instead, kick back with an endless supply of doughnuts?

Their limited ability to help people doesn't dampen the enthusiasm once they hit Tampa in the late afternoon.

Ambassadors scout out the territory and begin making their presence known, as street vendors start staking their claim to areas along the next day's parade route.

Gallegos stands on a corner and holds up a sign announcing the end. A man in a truck spots the warning, leans out his window and screams, "Amen, amen, amen!" Gallegos, thrilled to have found a friend and taker, darts out into the street toward the truck, tract in hand.

Nearby stands Tony DeLLomo, 63. He sports a white sweatsuit with the words "Jesus is King of Kings" emblazoned in red across his chest, as well as a matching sweatband on his head that reads "Jesus saves." He's a fan of Family Radio and other ministries working in partnership to preach the same doomsday message -- organizations that include eBible Fellowship, Latter Rain, Bible Ministries International and WeCanKnow.com.

Ambassadors point to the existence of other like-minded groups as evidence that Family Radio is not a cult. Adds Camping, the head of Family Radio: "I don't have anybody under my control. They're volunteers. I'm just a teacher. I'm just showing them where to look in the Bible. The Bible is the authority."

Scholars say predictions of the end have come and gone throughout history, and Camping's latest interpretation is just one to add to a list that will continue to grow.

But DeLLomo doesn't care about what's happened, or not happened, in the past. He's been on the road warning of the end for 13 years, he says, before boasting -- with a smile -- that he'd just been kicked out of a Super Walmart.

Driving RV No. 15 through downtown Tampa as the sun sets and night falls, Liquori explains that security at malls and stores like Walmart -- among the places they like to frequent -- can pose obstacles when spreading the news.

"We try to obey the law of the land as much as possible, but when it comes to getting out the gospel, we must obey God, not man," he says.

They circle the darkening city streets in formation, the reflective lettering on their RVs shining brightly, hoping to inspire "shock and awe," Liquori says.

They want dropped jaws, pointed fingers, whipped-out cameras. But on this night, when most residents are likely home gearing up for Gasparilla, ironing their ruffled shirts and polishing their black boots, the reaction is negligible. The few people the RVs pass seem unfazed by the warning.

"I've learned to keep my expectations low. I don't want this to be an emotional trip," Liquori says, looking ahead to the next day's event. "I expect it's going to be a tough crowd. From what I've heard about Floridians, they can have attitudes and be feisty."

Swilling beer and scripture

The pirates arrive early, as do the warnings.

Arianna Ramrajie, of Ocala, Florida, has one she'd like to share.

On May 21, the sun will "turn red like blood," the Earth will open up, bodies will be strewn about and "some people will die for eternity," she says.

"It scares me a little bit because some people are going to die, and I think I'm one of them," she adds. "I'm trying to do good things, but I'm afraid I'm doing something bad."

Arianna is 7, after all, and being good all the time cannot be easy. Her father stands next to her, nodding his approval.

She and her family, who've come in to help for the day, wander off to pass out tracts amid people wearing tricorn hats, carrying plastic swords and swilling beer and cocktails.

Some ambassadors look for good corners to claim, as does a man dressed as a chicken who is here to announce his own awesome news: the opening of a nearby restaurant.

Keitt loads up his backpack with freshly folded tracts and prepares to face the growing throngs.

"I can't spend that much time with each person. It's all about numbers," he says. "You really have to be assertive in a crowd like this because they're so focused on one thing. Gasparilla -- and drinking."

As he rushes down a sidewalk, a man walking behind him pulls up his eye patch to read the warning on the back of Keitt's shirt and mutters, "Damn, you're depressing me."

Taking his spot, Keitt gets to work, armed with a stack of tracts.

"How about you ma'am? We're giving these out all over the country," he says to one, hand extended. "Will you be the fortunate one?" he asks another. "We're going all over the country with this message," he offers a third.

Plenty take the tracts, though many look at them confused -- or perhaps that puzzled look is just the beer talking. Others whisk by and ignore him. Some cry out that they're banking on the Mayans to give them another year. The ambassadors, of course, pooh-pooh talk of the world ending in 2012. Their RVs advertise their dismissal of that date by featuring the year 2012 circled in red with a slash through it.

One man takes a tract, looks at Keitt and says, "I'll put it on my calendar and come back on May 22 to see if you're still here."

Most of the ambassadors refuse to even think about waking up on May 22. They believe Christ will return on May 21, the Day of Rapture, that they will be saved and taken up to heaven, and that those left behind will face unspeakable suffering until the world ends.

"If I'm here on May 22, it simply means I wasn't one of the elect," Keitt tells us.

Screaming and reaching

A pirate ship rolls up the street, blaring the hip-hop hit, "Party Like a Rockstar," by the Shop Boyz. College students bump and grind, raise their hands in the air and toss back beers. Two young men embrace in a passionate kiss.

On the other side of the parade route, 7-year-old Arianna is dancing, too. She's beside her sister, pressed against the barricade, screaming and reaching for flying beads. She's laughing. She's in the moment. She's being a kid.

Behind her stands her father, his face serious, his arms crossed.

Later, beside a Family Radio RV, Arianna beams and shows off all her beads, the multitude that drape her neck and the tangle of colors that fill her little shoulder bag.

She reaches in, scoops out a handful and giggles as a long strand falls to the ground.

Buried beneath the bounty in her bag lies a reminder of the serious responsibility that awaits her in the coming months: A stack of tracts, announcing the end is near.