ATLANTA — The Chick-fil-A sandwich — a hand-breaded chicken breast and a couple of pickles squished into a steamy, white buttered bun — is a staple of some Southern diets and a must-have for people who collect regional food experiences the way some people collect baseball cards.

New Yorkers have sprinted through the airport here to grab one between flights. College students returning home stop for one even before they say hello to their parents.

But never on Sunday, when the chain is closed.

Nicknamed “Jesus chicken” by jaded secular fans and embraced by Evangelical Christians, Chick-fil-A is among only a handful of large American companies with conservative religion built into its corporate ethos. But recently its ethos has run smack into the gay rights movement. A Pennsylvania outlet’s sponsorship of a February marriage seminar by one of that state’s most outspoken groups against homosexuality lit up gay blogs around the country. Students at some universities have also begun trying to get the chain removed from campuses.

“If you’re eating Chick-fil-A, you’re eating anti-gay,” one headline read. The issue spread into Christian media circles, too.

The outcry moved the company’s president, Dan T. Cathy, to post a video on the company’s Facebook fan page to “communicate from the heart that we serve and value all people and treat everyone with honor, dignity and respect,” said a company spokesman, Don Perry.

Providing sandwiches and brownies for a local seminar is not an endorsement or a political stance, Mr. Cathy says in the video. But he adds that marriage has long been a focus of the chain, which S. Truett Cathy, his deeply religious father, began in 1967.

The donation has some fans cheering and others forcing themselves to balance their food desires against their personal beliefs.

“Does loving Chick-fil-A make you a bad gay?” said Rachel Anderson of Berkeley, Calif. “Oh, golly, human beings have an amazing capacity to justify a lot of things.” Ms. Anderson has been with her partner for 15 years. They married in California during the brief period when same-sex marriage was legal in 2008. They have 7-year-old twins. A visit to her spouse’s family in North Carolina always includes a trip to the chicken chain.

But as she learns more about the company, Ms. Anderson is wavering about where to eat when they travel to Charlotte in April.

“I’m going to have to sit with this a little bit,” she said.

On the other hand, Rhonda Cline, a dental hygienist in Atlanta and a devout Christian, has only gotten more outspoken in her support. She was one of nearly a thousand people who logged onto the Chick-fil-A Facebook page to comment on the issue.

“I applaud a company that in this climate today will step out on a limb the way the Constitution allows them to,” Ms. Cline said in an interview. “This is the United States, so we should be able to practice our business the way we like.”

But religious values are not the main reason Ms. Cline goes to Chick-fil-A.

“I’m in a crunch at lunchtime, and these people are fast and they are smiling and they act like they are really happy you’re there,” she said.

Chick-fil-A runs 1,530 restaurants in 39 states, but it still feels like a hometown restaurant to fans in Georgia, which has 189 outlets. Sales figures for 2010 will most likely be over $3.5 billion, a spokesman said.

S. Truett Cathy, the founder, is an 89-year-old, Harley-riding Southern Baptist who opened a small diner near the Atlanta airport 1946. He closed the business on Sundays because he was a churchgoer who wanted a day to rest and be with his family.

Because the company remains privately held — his two sons run it — it can easily keep its faith-based principles intact. The company’s corporate purpose is, in part, “to glorify God by being a faithful steward of all that is entrusted to us.”

With its near-national reach and its transparent conservative Christian underpinnings, Chick-fil-A is a trailblazer of sorts, said Lake Lambert, the author of “Spirituality, Inc.” and dean of the college of liberal arts at Mercer University, where he teaches Christianity.

“They’re going in a direction we haven’t seen in faith-based businesses before, and that is to a much broader marketing of themselves and their products,” he said. “This is possibly the next phase of evangelical Christianity’s muscle flexing.”