God and country are persistent themes in President Trump’s rhetoric. In his inaugural address, he predicted Americans “will be protected by God.” He told a crowd at Liberty University that the country is “a nation of true believers.” He often links God and the military in a way that appeals especially with his evangelical supporters. “We are and will always be one people, one family, and one glorious nation under God,” he announced in his most recent Fourth of July message. He tweeted that he and his fellow citizens would think of the men and women serving in the military and “thank GOD for blessing us with these incredible HEROES!”

On a recent trip to Europe, Trump complained that NATO was being “unfair to our country” and explained, “I think we have a lot of foes. I think the European Union is a foe.” He toned down the nationalist rhetoric dramatically at a press conference with Vladimir Putin, perhaps because the Russian president embodies the strongman persona Trump himself has been trying to cultivate. Trump has repeatedly argued that when America remains true to its faith and traditional values, God will bless the country with the might to defeat its foes. And his words resonate with Christian nationalists—those who believe the United States was founded as a Christian nation and must continue to be one—because they tie together so many of the Christian Right’s beliefs and instincts. We have good reason to believe that Christian nationalism is one of the reasons evangelicals overwhelmingly support Trump.

We also have good reason to believe that religious folks who offer the clearest alternative to Christian nationalism are some of Trump’s most stalwart opponents. In May, American clergy issued the “Reclaiming Jesus” manifesto, which rejected Trump’s nationalist slogan of America First “as a theological heresy for followers of Christ.” The signatories included the Rev. Michael Curry, who preached at the recent royal wedding. In the “Reclaiming Jesus” statement, he and 22 other clergy reminded Americans: “Our churches and our nations are part of an international community whose interests always surpass national boundaries.” They went on to say, “We, in turn, should love and serve the world and all its inhabitants, rather than seek first narrow, nationalistic prerogatives.”

Not surprisingly, a conservative Catholic ethicist, writing for Breitbart, attacked this “globalist worldview.” “According to traditional Christian theology,” the author insisted, “a political leader’s first responsibility is to ensure the safety and well-being of his own citizens.”

These disagreements are nothing new to Americans. In fact, these two ways of looking at the world—Christian nationalism and globalism—arose decades earlier and in conversation with one another.

Christian Nationalism has taken many forms over the years and certain versions of it are older than the United States itself. There was a widespread belief among Puritan settlers in the 1600s that they had a special covenant with God and were called to be an example to the world. From the founding of the country onward, some Christians believed that the United States was a “city upon a hill,” an idea that is often called “American exceptionalism.” But as Abram Van Engen points out, American exceptionalism is not the same as the Christian nationalism of “America First.” The paranoia and conspiratorial instincts of today’s Christian nationalism came about in the twentieth century in response to the same things that Trump attacks today, like global capitalism and international organizations.

Christian nationalism was widespread during World War I. It was heard in churches, universities, tent revivals, and in the military because American Christians so enthusiastically agreed with Woodrow Wilson that the war was a humanitarian cause to save Europeans from German aggression and to make the world more democratic. In 1918, evangelist Billy Sunday announced that the war was “Germany against America, Hell against Heaven.” Navy chaplain Henry Van Dyke added another verse to The Battle Hymn of the Republic, which was sung by American sailors during the war:

We have heard the cry of anguish,

From the victims of the Hun,

And we know our country’s peril

If the war-lord’s will is done

We will fight for world-wide freedom

Till the victory is won

For God is marching on

It took years for words like these to sound off-tune to American ears but, by the 1930s, many American Protestants had become embarrassed by their earlier belief that their nation was spreading Christian civilization throughout the world. They enthusiastically backed the League of Nations, a precursor to the United Nations. Pacifism suddenly became popular. Congressional committees investigated the causes of World War I and concluded that it was bankers and munitions dealers who led young Americans into needless slaughter in Europe. American Christians began taking more seriously the idea that there should be some separation between religion and nationalism.

In the 1930s, some American Protestants began, for the first time, to think about Christianity as a truly global community. Of course, they had sent missionaries abroad for years and spoke out against inhumane treatment of people overseas, but in the 1930s, they came to believe that the world was an intertwined whole, and they began to see global interdependence to be in conflict with nationalism.

It wasn’t just religious leaders who believed this. According to historian Or Rosenboim, intellectuals across the United States and Great Britain perceived “a growing tendency towards technological, economic, cultural, and political interconnectedness, which for many mid-century thinkers gave rise to a new political concept, the global.” Some American Protestants looked at the turmoil in Asia and Europe and blamed the aggressive behavior of Japan and Germany on unlimited national sovereignty. Because each nation could do what it pleased, international relations were essentially lawless.

Even hawks, like Presbyterian layman and future Secretary of State John Foster Dulles, came to see nationalism as a problem. He had been involved in the creation of the League of Nations but in 1937 condemned the organization as a “rededication of the nations to the old principles of sovereignty,” of “unchanging and unchangeable compartments, the walls of which would continue as perpetual barriers.” He wanted to keep countries from acting in their own self-interest and instead to work for the common good on behalf of all of humanity.

Dulles would go on to mobilize America’s churches in the 1940s on behalf of the United Nations and the Universal Declaration of Human Rights, hoping to curb Christian nationalism by reminding Americans that they were part of an international community. Having learned from earlier mistakes, Dulles and his allies had backed America’s involvement in World War II on the condition that the United States begin building a permanent peace “along internationalist lines of global interdependency, as a nation among nations,” according to historian Andrew Preston.

Others went in the opposite direction. “America First” became a buzzword in the late 1930s as activists organized to keep the United States out of World War II. These leaders wanted to keep America isolated from affairs in Europe and Asia. Figures like the Catholic radio priest Charles Coughlin regularly told an audience of millions that an international conspiracy of Jews and monied interests were plotting against America. Protestant fundamentalists, meanwhile, viewed the world through an apocalyptic lens, worrying that the League of Nations and the Roosevelt administration were conspiring against the United States and getting ready to bring about the Antichrist.

In the 1950s, evangelist Billy Graham tried to remake the fundamentalist tradition by moving it away from its earlier bigotry and conspiratorial thinking. He was only partly successful. Such views persisted on the fringes of evangelicalism (and returned to mainstream evangelicalism in the 1970s). As importantly, the suspicion of international institutions persisted at the very center of evangelical life. In 1945, a columnist for the official journal of the National Association of Evangelicals said of the United Nations: “[F]rom the very start we hail it as godless, as a child of illegitimate alliances, born lame and due to die in the further catastrophes that come upon the earth.” Evangelicalism remained squarely in the Christian nationalist camp.

The two poles of globalism and nationalism grew in tandem, with one reacting to the other. As Protestant globalists encouraged the United States to join an international community, Christian nationalists reacted by trying to seal off America’s borders. Globalism and nationalism were by no means absolute. Like today, vast numbers of religious people in the United States subscribed to neither view in the 1930s and 1940s, and they changed their values and opinions with the changing times. John Foster Dulles himself showed that the boundaries between globalism and nationalism were porous, as he became in the 1950s on of the most stalwart defenders of American sovereignty.

And that may be part of the problem. Without a clear stand on questions of nationalism, religious groups sway from one extreme to the other with the changing times, unable to offer much resistance to the general mood of the country and the machinations of politicians. That was certainly the case during the Cold War, as religious folks celebrated America and its war against godless communism. Many of the same churches changed their tune in the 1960s, when widespread protests took place against the Vietnam War.

The fight goes on even today. In thinking about Christian nationalism, I am reminded of a visit I made to a North Carolina church in 2006. It held about 500 people, and it had two large screens on either side of the pulpit. The service was just before the Fourth of July and sounded much like Trump did in his Independence Day address. The pastor reminded congregants that the United States was founded as a Christian nation. Then the choir began singing:

“Off we go into the wild blue yonder / Climbing high into the sun / Here they come zooming to meet our thunder / At ‘em boys, Give ‘er the gun!”

It was the “U.S. Air Force” song and as it played, a veteran walked between the pews toward the pulpit waiving the Air Force flag and the two screens played footage of bombers dropping ordinance on Iraqi targets during Operation Desert Storm. The scene repeated for the Army, the Navy, the Marines, and finally the Coast Guard. After the nationalist display, the service ended with a few hymns, including, without any obvious irony, “Down by the Riverside” (“I’m gonna lay down my sword and shield down by the riverside / Ain’t gonna study war no more”).

I imagine that ten years later, in the age of Trump, the president enjoys widespread support at this church, since he enjoys broad appeal with white evangelicals across the country. And I imagine the minister would cheer the president’s militaristic rhetoric. In retrospect, it’s easy to see how the Christian nationalism I witnessed in 2006 paved the way for today’s politics.

Gene Zubovich is a visiting fellow at the University of Toronto. He writes on the history of religion and politics. Follow him on Twitter: @genezubovich