What is it about Donald Trump that has even Pope Francis suggesting that he "is not Christian"? As the Washington Post notes, Francis is the latest on a list of world leaders who have denounced Trump. 

We can't be surprised at the positions Trump is taking on immigration because there's always been an anti-immigration strain in American politics. There is something more to it,  I think. It's the utter contempt he summons up in his delivery: the face screwed into a mask of resentment, the grimaces, the clenched jaw, the jabs. And oh yes, the vocabulary: an act contrived to induce fear and loathing on the campaign trail (nowadays known as appealing to the base.) That's why so many world leaders are reacting as they do: They recognize that a demagogue is advancing toward the Oval Office.

In a column in the New York Daily News last July, Cardinal Timothy Dolan  cast Trump as a modern-day nativist of the sort who in the past “organized, white, Protestant antagonism toward the Catholic immigrant.” Dolan, who taught church history, recalled how his students would not believe him when he said nativist bigotry remained alive in America. But now, Dolan wrote, he has his "Trump card" for that debate. "Nativism is alive, well — and apparently popular!" he wrote.

Dolan didn't flat out say  Trump was being un-Christian. But he wrote, "I am not in the business of telling people what candidates they should support or who deserves their vote. But as a Catholic, I take seriously the Bible’s teaching that we are to welcome the stranger, one of the most frequently mentioned moral imperatives in both the Old and New Testament."

That's similar to what Pope Francis said to reporters on the flight home from Mexico: "And then, a person who thinks only about building walls, wherever they may be, and not building bridges, is not Christian. This is not in the Gospel. As far as what you said about whether I would advise to vote or not to vote, I am not going to get involved in that. I say only that this man is not Christian if he has said things like that. We must see if he said things in that way and in this I give the benefit of the doubt."

Trump has some Catholic defenders, such as Bill Donohue of the Catholic League, who views it all as a media-perpetrated misunderstanding. And the two Catholics running for the GOP nomination found themselves in the awkward position of defending their rival Trump against the pope.

They obviously expect Republican primary voters to reject the pope's critique. But it's a long election season, and as the general election approaches, I think that what happened today will matter. The Republican appeal to Christian faith to mobilize voters will not be quite the same.