For any other politician, President Trump’s response this week to a question about his faith would have inspired cringing from religious Americans.

During an interview being conducted by Sean Spicer, his former press secretary asked if Trump had grown in his faith.

“I think maybe I have, from the standpoint that I see so much that I can do,” Trump replied. “I’ve done so much for religion. The Johnson amendment. Getting rid of Mexico City. Nobody thought any of this stuff would happen. Two Supreme Court justices."

“By the way,” he continued, “if the other side — and I call them the radical left because, [former vice president Joe] Biden has gone way left but he doesn’t know where he is. But he’s surrounded by people that are put there that are serious radical left. You won’t have a Second Amendment. You won’t have religious liberty. You won’t have anything.”

That, in a nutshell is the case Trump makes to conservative religious voters. They know that his life isn’t an ideal model of their values and he knows that they know that. But he also knows that continuing to deliver conservative judges, a platform for the antiabortion movement and a focus on empowering religious institutions and actors will endear them to him.

He knows, too, that evangelical voters would prefer an occasionally religious president who consistently prioritizes their concerns to a pious Democrat who’s more socially liberal. It’s important to note that white evangelical Protestant Americans aren’t unusually supportive of Trump simply because of religion. It’s also because they’re heavily Republican, as Pew Research Center data released last year indicate. Among white evangelical Protestants, 77 percent identify as Republican or Republican-leaning — a remarkably dense overlap of religion and party.

On Thursday, the New York Times reported a sudden sign of shakiness within this group. Polling from PRRI released this week indicates that approval of Trump among evangelical voters has fallen nearly 20 points since March. Among white Catholics, the decline has been nearly as sharp.

As the Times’s Jeremy Peters notes, that’s significant. An analysis of the 2016 electorate completed by Pew shows that white evangelicals and white Catholics were more supportive of Trump than any other religious group. He won the latter group by 33 points and evangelicals by 61 points over Hillary Clinton.

More important, Pew’s data suggest that more than half of the votes Trump received that year came from voters who fit into one of those two groups. A fifth of his support was from white Catholics. Fully a third was from white evangelical Protestants.

Erosion in his approval among those two groups, then, is significant. Lose 20 percent of his support from black Protestants and he’s losing … well, we don’t know since his support from that group was hard to measure in the first place. Lose 20 percent of his Catholic support, though, and he’s risking 4 percent of his overall support.

There are some important caveats, though. One is that the decline since March measures current approval relative to a recent peak. PRRI also has data from 2019; comparing the most recent evangelical support to that figure shows a drop of only 2 points among evangelicals. Among Catholics, the drop is still 12 points — a less problematic drop, but still a problematic one.

To Trump’s point, there’s also the question of what a drop in approval from these core constituencies means. If it means they are slightly less enthusiastic about voting for him than they might otherwise be, so be it. A vote is a vote, even a grudging one. As we’ve noted, Trump’s 2016 victory can be attributed to voters who disliked both him and Clinton but voted for him anyway. An evangelical whose view of Trump is lukewarm but votes for Trump is a vote for Trump. That evangelical is not likely to demonstrate that lack of enthusiasm by voting for Biden.

The problem with a drop in approval is less losing votes to Biden than losing votes because people stay home. The opposite of wanting to vote for someone isn’t necessarily voting for his opponent; it can also be not voting at all. That’s the concern Trump’s team should worry about. Lose 10 percent of Catholic voters who simply don’t feel motivated to vote at all, and you’re still shedding 2 percent of your 2016 electorate.

This is the part of articles about general election polling in which we note that there are months to go and billions of dollars still to be spent. If the election were held today, polling suggests that Biden could win by a double-digit margin nationally, the sort of margin which makes slight erosion from a religious demographic irrelevant.

That said, the poll above does suggest a few ways in which Trump might want to spend those months and those dollars: ads highlighting the message he offered Spicer.