Chick-fil-A founder S. Truett Cathy has died at age 93. The fast food chain known for its mix of religion and business made headlines in 2012 when its president made statements opposing same-sex marriage. (Reuters)

S. Truett Cathy, who became a billionaire as the founder of Chick-fil-A Inc., the closely held fast-food franchise known for its “Eat Mor Chikin’ ” slogan and for staying closed on Sundays to reflect Mr. Cathy’s Southern Baptist faith, died Sept. 8 at his home in suburban Clayton County, south of Atlanta. He was 93.

The company announced the death but did not cite a cause.

The chicken chain that Mr. Cathy started in Georgia in 1946 grew to more than 1,800 restaurants in 39 states and the nation’s capital, according to the Atlanta-based company’s Web site. Chick-fil-A is valued at about $5.5 billion, according to data compiled by Bloomberg. Cathy had a net worth of $1.9 billion, according to the Bloomberg Billionaires Index.

[The world according to Chick-fil-A founder Truett Cathy]

The prospect of an even bigger payday never persuaded Mr. Cathy, the longtime chairman and chief executive, to take his company public. Doing so, he said in a 1998 interview, would mean giving up family control of matters such as contributions to charity and remaining closed on Sundays.

“As a public company, I’m sure somebody would object to our generosity,” he said.

Even as it expanded nationwide, Chick-fil-A remained a distinctly Southern institution, one that generated fierce loyalty among its customers. In 1982, the company adopted a two-sentence corporate mission: “To glorify God by being a faithful steward of all that is entrusted to us. To have a positive influence on all who come in contact with Chick-fil-A.”

Mr. Cathy and his family drew notice for their philanthropy through their WinShape Foundation, which offers scholarships and funds foster homes. Their donations to religious organizations active in the debate over the definition of marriage landed the family, and Chick-fil-A, in the middle of an uproar during the 2012 U.S. elections.

In response to reports about the family’s support for groups fighting legalization of gay marriage, Dan Cathy, who succeeded his father as chairman and chief executive, said: “Well, guilty as charged. We are very much supportive of the family, the biblical definition of the family unit,” according to the Biblical Recorder, a newspaper for North Carolina Baptists.

Gay rights groups, which for years had pointed out that Chick-fil-A’s charitable arm gives millions of dollars to Focus on the Family, the Eagle Forum, the Family Research Council and other organizations opposed to gay marriage, urged a boycott of the chain and kiss-ins at the restaurants. Former Boston mayor Thomas Menino sent a letter urging the company to back out of plans to locate in his city, and the Jim Henson Co. pulled its Muppet toys from kids’ meals.

Opponents of gay marriage, including Rick Santorum, Sarah Palin, Billy and Franklin Graham and former Arkansas governor and talk-show host Mike Huckabee, voiced their support for the chain.

The company, responding to the outcry, issued a statement saying its policy is to “treat every person with honor, dignity, and respect — regardless of their belief, race, creed, sexual orientation, or gender.”

The controversy later subsided.

Samuel Truett Cathy was born on March 14, 1921, in Eatonton, Ga., one of seven children of Joseph Benjamin Cathy and the former Lilla Kimbell.

Starting at age 8, he sold soft drinks and magazines, and then began delivering newspapers, winning awards for signing up new Atlanta Journal subscribers, according to his family’s Web site. His mother took in boarders to help pay the bills.

Mr. Cathy was drafted into the Army after graduating high school and served until 1945, according to the family Web site.

The following year, he and his brother, Ben, opened a small diner called the Dwarf Grill, later the Dwarf House, in the Atlanta suburb of Hapeville; the eatery was named for the short and stout shape of the building.

The original menu consisted of hamburger and steak plates and a chicken-salad sandwich. Ben Cathy and a third brother, Horace, both amateur pilots, were killed in a crash of their private plane in 1949, according to the Atlanta Journal-Constitution.

It wasn’t until the early 1960s that Truett Cathy began work on a fried-chicken sandwich, after the owners of a local poultry purveyor came to him with surplus boneless breast pieces.

Mr. Cathy, whose mother had fried chicken in a skillet with the lid on to keep it moist, began using a recently invented commercial pressure cooker, the Henny Penny, that allowed him to fry a boneless, skinless chicken breast in just four minutes.

After tinkering with his seasoning mix, Mr. Cathy put the result on a buttered bun, added pickle slices “to give the sandwich character,” and, at the suggestion of his lawyer, came up with the name Chick-fil-A — the final “A” a measure, he said, of the sandwich’s quality.

Mr. Cathy opened the first Chick-fil-A restaurant, in an Atlanta shopping center, in 1967, before food courts became a standard service in malls. During the next 20 years, Mr. Cathy added 350 more plaza restaurants. When mall development slowed in the 1980s, Mr. Cathy turned to free-standing stores. He also opened restaurants on college campuses and inside hospitals and grocery stores.

With his wife, the former Jeannette McNeil, he had three children. Sons Dan and Don, who is known as Bubba and is senior vice president of Chick-fil-A, and daughter Trudy Cathy White, who became girls’ director of WinShape’s summer camps.

Mr. Cathy’s sympathy for children was demonstrated in August 2008 when he worked out a deal with the parents of two girls who were accused of causing $30,000 in damage to a home he owned in New Smyrna Beach, Fla., according to the Associated Press. The girls were banned from watching TV and playing video games. They also had to write “I will not vandalize other people’s property” 1,000 times, the AP reported.

He told the Daytona Beach News-Journal that he didn’t want to have them prosecuted and left with a criminal record.

As the author of several books, his 2007 book “How Did You Do It, Truett?” outlined his strategy for success that included setting priorities, being courteous, cautiously expanding a business and not being burdened with debt.

“There’s really no secret for success,” he said then, according to the AP. “I hope it will open eyes for people. They don’t have to follow my recipe but this is what works for me.”

— Bloomberg News