Donald Trump took a break from threatening to sue rival candidates on Thursday and appears to be trying to start a holy war with Pope Francis instead. Trump may not care about any resulting eternal judgment, but he might have reason to worry about worldly opinion: Pope Francis has a net +53 favorability rating among Americans, while Trump has a net -27 favorability rating.

True, Pope Francis is somewhat less popular with Republicans than among Americans overall. But he’s still reasonably well-liked. In a CNN poll in September, 56 percent of Republicans had a favorable view of Pope Francis as compared to 21 percent with an unfavorable one. Francis had +20 net favorability rating even among self-described tea-party supporters.

For once, this is a fight that Trump didn’t start. Reporters asked Pope Francis, during one of the informal press conferences held on the papal plane what he thought of Trump’s position on building a wall at the U.S.-Mexico border. The pope said that he wasn’t familiar with Trump’s position, but added, “I say only that this man is not Christian if he has said things like that.”

The majority of conservative Catholics would probably agree with that assessment of Trump’s faith. According to a survey conducted in January by the Pew Research Center, just under half (49 percent) of Catholics who are Republicans or lean toward the GOP said that Trump was not very or not at all religious. That was the highest level of skepticism expressed by any of the denominations Pew surveyed. (White mainline Protestants were most likely to give Trump the benefit of the doubt; 35 percent judged him to be not very or not at all religious.)

However, a sizable share of Catholics are open to seeing Trump in the White House, even if they don’t expect to see him in a pew. In Pew’s survey, 30 percent of all Catholics who are registered to vote said they felt that Trump would be a good or great president. That’s pretty much on par with registered voters in general (31 percent). In other words, Catholics are swing voters. In 2012, Catholics gave 50 percent of their votes to Barack Obama and 48 percent to Mitt Romney, according to the national exit poll.

Trump doesn’t need to worry as much about winning over Catholics in coming weeks. The next set of GOP primaries doesn’t occur in heavily Catholic states. Super Tuesday’s contests on March 1 will include Massachusetts, where Catholics made up 51 percent of Republican voters in 2008, but most of the upcoming states are in the South, where few Catholics reside.

STATE WINNER AMONG CATHOLICS (2008) CATHOLIC SHARE OF GOP ELECTORATE (2008) New Jersey McCain 57% Massachusetts Romney 51 New York McCain 46 Connecticut McCain 45 Wisconsin McCain 39 New Hampshire McCain/Romney tie 38 Vermont McCain 35 Maryland McCain 33 Louisiana McCain 32 Illinois McCain 31 Florida McCain 30 Michigan Romney 29 Delaware McCain 28 Ohio McCain 26 California McCain 25 Missouri McCain 20 Arizona McCain 20 Virginia McCain 19 Nevada Romney 18 Texas McCain 16 South Carolina McCain 13 Oklahoma ** 11 Georgia Romney 11 Mississippi ** 9 Tennessee McCain 6 Arkansas ** 6 Alabama ** 5 Utah ** 3 Where are the Republican Catholics? ** Sample size too small to reliably determine winner among Catholics Source: Edison/Mitofsky National Election Pool Exit Polls, 2008

But although the Catholic-heavy states fall later, they could prove important to the delegate math. Many of their delegates are awarded on a winner-take-most (as in New York, where 46 percent of the Republican electorate was Catholic in 2008) or winner-take-all (as in New Jersey, Wisconsin and Pennsylvania) basis. So if Trump doubles down on his fight with the pope, he could wind up paying a price as he seeks to expand his coalition beyond his enthusiastic base — particularly given that he may already have a relatively low ceiling on his support. In 2008, another competitive primary (and one with more comprehensive exit polling than 2012), Catholics were an important part of John McCain’s coalition, and they’re a group that a candidate like Marco Rubio (who is Catholic) or John Kasich could come to rely upon this year.

Plus it’s just plain inaccurate to complain, as Trump did, that “for a religious leader to question a person’s faith is disgraceful.” For someone whose titles include Vicar of Jesus Christ and Successor of the Prince of the Apostles, questioning and clarifying other people’s faith is pretty much the job description.