Stanley Brown was up late on Thursday, monitoring all the news about the new pope, Leo XIV, including revelations that he grew up as a Chicago White Sox baseball fan. As soon as Mr. Brown heard that, he knew something very important.

“If he’s a White Sox fan, then he can identify with suffering,” said Mr. Brown, 72, a village trustee in Dolton, Ill., the town where the pope grew up. “But it doesn’t matter how bad they are, we stay loyal as Sox fans. That’s not something you just give up.”

Chicago has long been divided between its two baseball teams, the White Sox on the South Side and the Cubs on the north. Both are known more for losing than winning over their century-plus histories. But the Northsiders usually attracted more attention as the cuddly, lovable Cubbies, with their boutique stadium, afternoon games, celebrity renditions of “Take Me Out to the Ball Game” and the hand-operated scoreboard at Wrigley Field.

The White Sox, playing inside a less charming stadium in a grittier part of town, are far from chic. But there is an unmistakable pride held by their fans, especially now.

The Cubs may have won the World Series more recently, in 2016, and may be considered a more fashionable brand. But the White Sox have the pope.

“That tells you he’s a real person,” said Courtney White, an athletic coordinator for youth sports in Dolton. “I mean, he’s from Dolton and he’s a White Sox fan. You can’t get more real than that.”

Being a White Sox fan is not easy. It requires devotion, loyalty, faith and above all else, forgiveness. It almost sounds like an internship for a job at the Vatican.

Pope Leo was born Robert Francis Prevost and grew up in a modest single-family house at 212 141st Place in Dolton, a middle- and working-class town just across the line from Chicago’s southern boundary. As soon as he was named pope on Thursday and identified as a Chicagoan, one of the first things people here wanted to know was, Sox or Cubs?

At first, rumors circulated that he was, gasp, a Cubs fan. But his brother John Prevost explained on WGN in Chicago that, although their mother’s family was from the North Side and harbored allegiances to the Cubs, the pope favored the White Sox (their father was a Cardinals fans, appropriately enough for the father of a prelate).

By Friday evening, his White Sox bona fides were validated. While living in Rome in 2005, he managed to make it to Game 1 of the World Series in Chicago. He was even spotted in the stands during the national television broadcast. The White Sox won the game, 5-3, and went on to sweep the Houston Astros for their first World Series title since 1917.

Pope Leo was born in 1955, amid a run of relative success for the White Sox. Weeks after he turned 4, they made it to the World Series, losing to the Los Angeles Dodgers. They were decent over the next few years but weren’t able to make it back to the World Series again until 2005.

Robert Prevost was not particularly interested in playing sports, according to his friend, James Priestley, 69, a lawyer from Naperville, Ill., who attended both a seminary high school in Michigan and college at Villanova with the pope. Bob, as Mr. Priestley knew him, was more passionate about academics, philosophy and spiritual matters than who stole the most bases in 1961 (it was Luis Aparicio of the White Sox).

“I would say there is really no sports angle here,” Mr. Priestley said. “He was always such a sweet, caring, intellectual guy, exactly the kind of person you hope would become pope. But he didn’t talk much about sports, that I recall. If you asked him about Catholic doctrine or something like that, he could talk all day about that.”

When they attended St. Augustine Seminary High School near Holland, Mich., a boarding school for boys, all students were required to participate in sports. Mr. Priestley recalled the pope participating out of obligation rather than passion. He also recalled an annual party among their peer group to watch a Chicago Bears football game, and the pope attended at least one of those.

Mr. Priestley, on the other hand, is a devoted White Sox supporter, who just watched his team lose four straight games this week, in typically sloppy fashion. This is an organization that set a record last season for most losses — 121. The White Sox today are in a familiar spot, last place in the American League Central. The Cubs are in first place in National League Central.

“The tradition says that the Cubs fans are snooty and soft and the White Sox fans are tougher,” Mr. Priestley said. “I don’t really buy into all that. But I can tell you that there are some Cubs fans in the southland suburbs. I don’t think there are too many White Sox fans to the north.”

On Friday, the White Sox played their first home game since the pope’s election. Ann Allie, 46, a physician from Chicago, said she was worried when she first heard that the pope was a Cubs fan.

“I was relieved when I heard he likes the White Sox,” she said. “It’s really cool, and it makes sense.”

Art Ortiz, a web designer at the game with his family, is a rare example of a White Sox fan originally from the North Side. But he was taken to a game as a child in the 1980s, and fell in love. He hoped the new pope might help the fortunes of his club.

“It’s a blessing,” he said. “And we need it.”

About 20 minutes south of the stadium, Dolton has a rich baseball tradition, too. One street is named after Lou Boudreau, the Hall of Fame player for Cleveland, who grew up in nearby Harvey, Ill. The Dolton Boys was a Little League powerhouse for many years, until fewer and fewer kids participated. Mr. White, the athletic coordinator, played through high school and was coached by Mr. Brown, the village trustee. They said they were negotiating with the nonprofit The Players Alliance to help revitalize baseball in the town.

“Baseball used to be everything, until they rolled out that basketball,” Mr. Brown said as he looked over one of the municipal fields where he coached both his son and Mr. White. “Now, it’s hard to get kids to play.”

A few blocks away, in front of the pope’s childhood home, several people came to visit on Friday. Some, like Ralph Pizza, 65, a retired architect, grew up a few blocks away on 146th St., and said he and most of his friends were White Sox fans. But he did know some Cubs fans there, too.

John Crowley, a retired electrician, is 68 and from the North Side. He roots for the Cubs but dared to make the trip south. He is also Catholic, and wanted to see the house where the new pope grew up. He is thrilled that Pope Leo is from the Chicago area, but not as much that he is a White Sox fan. He promised not to hold it against him.

“It’s OK,” Mr. Crowley said. “They can use the help.”