On Wednesday night, former football Coach Lou Holtz spoke at the Republican National Convention and questioned Joe Biden’s faith. “The Biden-Harris ticket is the most radically pro-abortion campaign in history,” Holtz said. “They and other politicians are Catholics in name only and abandon innocent lives. President Trump protects those lives.”

Joe Biden responded by saying, “I’m a practicing Catholic. I don’t proselytize about it.” He added, “I never miss Mass. It’s who I am.”

In truth, although no proselytizer, Biden is more open about his religious faith than any Democratic presidential candidate since Jimmy Carter, who famously defined himself as a born-again Christian.

Biden, if elected, would be only the second Catholic ever to be president. His Catholicism was repeatedly emphasized at the Democratic convention, especially by a leading surrogate, Delaware Senator Chris Coons.

“People, Joe believes, were made in the image of God. Joe learned that from his parents and the nuns and priests right here in Delaware, who taught him and inspired in him a passion for justice,” said Coons. “Joe’s faith is really about our future, about a world with less suffering and more justice, where we’re better stewards of creation, where we have a more just immigration policy and where we call out and confront the original sins of this nation, the sins of slavery and racism. Joe knows these are central issues in this election. And for him, they’re rooted in faith.”

Religion is a central fault line in American politics. Biden and Coons are articulating a version of liberal Christianity where faith is defined by private worship and actions to ameliorate the world. This stands in contrast to the conservative Christianity of Trump and Vice President Mike Pence.

The Trump/Pence version of Christianity is a fusion of religion with reactionary nationalism, where faith is defined by protecting a traditional way of life against foes both domestic and foreign. This way of life can be defined in simple shorthand as a nostalgic idealization of 1950s America, with the need to maintain rigid racial and gender hierarchies. This explains the importance Trump-supporting Christians give to issues like abortion, immigration (threatening because it changes the racial demography of America), and LGBT rights.

In his speech at the RNC on Wednesday night, Mike Pence said, “Let’s run the race marked out for us. Let’s fix our eyes on Old Glory and all she represents. Let’s fix our eyes on this land of heroes and let their courage inspire. And let’s fix our eyes on the author and perfecter of our faith and freedom and never forget that where the spirit of the Lord is, there is freedom—and that means freedom always wins.”

As The Washington Post reports, Pence’s words were a reworking of two Bible verses (2 Corinthians 3:17 and Hebrews 12:1-2) but with “Old Glory” replacing “Jesus.”

Pence is in effect defining American nationalism as holy, the literal equivalent of God. Some Christians find this equation of nation with divinity to be an affront to their faith. Greg Jao, senior assistant to the president of InterVarsity, a leading campus religious organization, tweeted, “Glad Pence seems to know Scripture; grieved & appalled he’d believe substituting ‘Old Glory’ for ‘Jesus’ wasn’t blasphemous and equating the freedom Paul was referring to with civil liberties.”

Because the faith Trump and Pence are selling is religious nationalism, Christian Republicans can easily reconcile themselves to supporting Donald Trump despite the fact that he is clearly a biblical illiterate and profane libertine. For Christian nationalists, religion isn’t a matter of going to church, having a decent personal life, or even working to make the world a better place. Faith, in this version of Christianity, is about keeping the nation powerful by buttressing traditional hierarchies. Trump fulfills the need for a nationalist strongman.

Integral to nationalism is an ideal of rugged masculinity that Kristin Kobes Du Mez, a historian who teaches at Calvin University, connects to classic Hollywood movies in her book Jesus and John Wayne. Speaking on NPR, Du Mez noted of the Wayne character that whether he is “on the frontiers of the Wild West or in the Second World War or on the battlefields of Vietnam, he can bring order through violence. And he can defend Christian America, really, and that’s what really appeals to many evangelicals, how he becomes this icon—and not just to evangelicals but to secular conservatives as well.”

There are tens of millions of Americans who aren’t Christian at all. But Christianity remains the majority religion, so the two parties are offering starkly different versions of the faith. Biden is the avatar of a Christianity of good works, Trump of a Christianity of violence unleashed against all perceived enemies.

Many of Trump’s supporters see his victory in 2020 as providential. But if Trump loses this year, it’s unlikely that they’ll think God didn’t want Trump’s reelection. Rather, they are likely to redouble their holy war against liberalism.