OAK BROOK, Ill. — Six days a week, in fair weather and foul, two-dozen door-to-door salesmen, all of whom live clustered together in an apartment complex in this suburb west of Chicago, pile into S.U.V.’s and cars and head into the big city, bent on sales of home security systems.

And on Sunday, their one day off, they drive together to the nearest house of worship of the Church of Jesus Christ of Latter-day Saints.

The salesmen are mostly former Mormon missionaries from Utah who cut their teeth — and learned their people-skill chops — cold-calling for their faith. In Chicago and in its suburbs where their employer, Pinnacle Security of Orem, Utah, has shipped them for the summer sales season, they are doing much the same thing, but as a job.

“It’s missionary work turned into a business,” said Cameron Treu, 30, who served his mission in Chile and was recruited into D2D (that is door-to-door in sales lingo) by another former missionary.

Managers at Pinnacle Security, founded in 2001 by a student at Brigham Young University, the Mormon Church-owned school, say missionaries simply have the right stuff. Many speak foreign languages learned in the mission field. All have thick skins from dealing with the negative responses that a missionary armed with a Book of Mormon and a smile can receive.

Mormon men are expected to serve a two-year mission in their early 20s, and about two-thirds of Pinnacle Security’s 1,800 sales representatives this summer have been through the experience. Former missionaries work for other direct-sales companies, too, though Pinnacle seems to be in a class by itself: It has deployed them in 75 cities nationwide.

“They’re used to knocking on doors, and they’re used to rejection,” said Scott Warner, Pinnacle’s manager of the Chicago sales team.

Mr. Warner said interest in the security products was up this year — a recession indicator, he said — as people reacted to fear (if not always a statistical reality) of rising crime. But the number of potential customers who cannot pass credit checks is up, too, with more homeowners unable to afford the $40 or so a month that Pinnacle charges to monitor a system. The company also charges a $99 installation fee, but nothing for the alarm equipment itself in a standard package.

As millions of traditional jobs dried up last year, at least 100,000 Americans joined the ranks of what is called, in the trade, direct sales. With items like cosmetics and skin care (Mary Kay, Avon) and housewares (Cutco knives, Fuller Brush), more than 15.1 million people are now selling something, or trying to, somewhere far beyond the mall.

And retention is up in a profession with a notoriously high burn-out rate, industry experts say. (Fifty to 100 door-knocks a day, with one or two completed sales, is an average grind.) At Pinnacle Security’s Oak Brook office, for example, only about 15 percent of the reps had given up and gone home, or not worked out to expectations, after the first month of the sales season, which began in early May — about half the normal attrition rate.

“Consumer companies and retailers are trying to break through the clutter, and it’s a lot easier for companies to recruit talent in this job market,” said Thomas Lutz, a senior partner in the Boston Consulting Group, which advises companies on growth and marketing.

Business is only part of the chemistry though. In a free-market economy, every sale or purchase is on some level an act of conversion, a matter of overcoming objections or hesitancy and getting to “yes.” Decision making and trust are never entirely matters of pure logic.

Matt Romero, a 24-year-old college student from Draper, Utah, south of Salt Lake City, admitted freely that in his heart he was still partly a missionary.

Mr. Romero is fluent in Spanish from his mission to Peru, eloquent and invariably polite in English in trolling the mostly black neighborhoods of Chicago’s South Side. He made $13,000 last summer selling 60 security systems for Pinnacle and is aspiring this year to sell 150 systems, which would trigger big incentive bonuses that could increase his pay to $75,000 or more.

But he said he was also ready to render unto God the things that are God’s.

His thinking on that question changed one afternoon in early May. A woman opened the door and wanted to talk about religion.

“She asked me if I believed in Christ and if I knew who my savior was and I said, ‘Yes, ma’am,’ and we had a discussion and she told me, ‘No one comes in my house without hearing the word,’ and I said, ‘That’s a good policy, ma’am,’ ” Mr. Romero said on a recent afternoon of knocking on doors.

“Since then, I’ve been carrying around these little cards,” he said, lifting up his stack of Pinnacle brochures to reveal a smaller stack of what are called “pass-along cards,” with facts and frequently asked questions about the Mormon Church. Marketing experts say that cold-calling in general has become more sophisticated since the era of Willy Loman, with training, mentoring and recruiting efforts sharpened at many companies. But Pinnacle’s salesmen are also applying skills learned in the mission field, like “mimic and mirror,” a technique of adapting one’s posture and bearing to the person being spoken to as a way of inducing trust — if his arms are crossed, you cross yours; if she tilts her head in asking a question, you do the same.

“Before my mission, I knocked on doors and I had some success,” said Matt Biesinger, 23, who worked a summer for Pinnacle before going to Paraguay as a missionary. “On the mission, I learned how to talk to people.”

Role-playing exercises conducted on many mornings reinforce those lessons. Look into a potential customer’s eye, trainers say, but do not stare, which can appear confrontational. When the door opens, always stand at a slight angle to diffuse any body language that might convey threat. And never diminish yourself by using the word, “just,” as in, “I’m just here in the neighborhood.”

Sometimes, though, it rains, and when it does, Pinnacle’s sink-or-swim mentality for sales reps, especially new, unproven ones like Brandon Rogers, is tough love at its toughest.

Newbies, for fear they may retreat to their cars, are dropped off and left on foot without shelter or access to a bathroom unless they can gain admittance into a house to make their sales pitch. Mr. Rogers, who is 21, had three energy bars and no umbrella to last him through a long, wet day.

He had made one sale by dark, when they picked him up.