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In his new book, Separating Church and State: A History, legal scholar Steven K. Green provides a comprehensive backstory to the fraught and turbulent historical relationship between religion and government in the United States. A concept important to many of the founders and firmly enshrined by past justices of the Supreme Court, the separation of church from state has stood upon increasingly shaky ground since its heyday in the 1940s and 50s. By the 1990s, Green writes, “A principle that had been at the heart of an important area of constitutional law was now openly reviled by opponents and all but abandoned by supporters.” In the early 2020s, its future appears terribly uncertain.

Green is the Fred H. Paulus Professor of Law and Affiliated Professor of History and Religious Studies at Willamette University. It’s a position he accepted after serving for 10 years as legal director and special counsel for Americans United for Separation of Church and State, an advocacy organization in Washington, D.C. His previous books include Inventing a Christian America: The Myth of the Religious Founding and The Bible, the School, and the Constitution: The Clash That Shaped Modern Church-State Doctrine.

Eric C. Miller spoke with Green about the book over Zoom. Their conversation has been lightly edited for length and clarity.

Religion & Politics: You write that the concept of church-state separation appears to be “on the ropes” under the Roberts Court. How so?

Steven K. Green: As a historian and a lawyer, one thing that I have found very curious is just how often the conservative members of the Supreme Court now criticize the idea of church-state separation, an idea that the Court did not create but has adopted and embraced ever since a unanimous decision back in 1947. The hostility that we are seeing from these justices seems to reflect a perspective that separation has somehow been forced upon the Court. Justice Thomas has been very critical and, as recently as January, Justice Gorsuch has referred in passing to the “so-called” separation of church and state. It’s very strange, because this is a principle that the Court has roundly endorsed over the years, but now they act like it’s an alien concept. The purpose of this book is not necessarily to get into a debate about the merits of separation, but rather to explore the bona fides of the principle as well as why it has become controversial.

R&P: What’s the origin story of church-state separation? Is it traceable directly to the Constitutional Convention, or only as far back as the Warren Court?

SKG: In this book I am very interested in the historical pedigree of the concept, and how it has evolved over time. I therefore open with some attention to the western Christian origins, dating back to the Middle Ages, when the Catholic Church was trying to free itself from the control of the Holy Roman Empire and so drew a line in the sand. St. Augustine wrote about the two cities separated by a wall, the one temporal and the other sacred. So, the concept goes back to the Church doctrine of separate spheres of influence. Later it acquired an Enlightenment strain. In each case it predates the colonies, and it certainly predates the Constitution. Now, there was nothing in the Constitution initially that dealt with religious issues except for the “no religious test clause” that was put into Article 6. Separation of church and state wasn’t really debated during the Constitutional Convention, though it would come up two years later with the drafting of the First Amendment. Even then, the phrase was not explicitly used.

R&P: You write that the French Revolution and Thomas Jefferson’s presidency each had profound effect on American attitudes toward the relationship between church and state. How so?

SKG: To this day, people continue to debate the religiosity of the founders—how religious they were, whether most were Christians or deists, whether religious influences informed the drafting of important documents like the Constitution, etc. To an extent, these are unwinnable debates. Clearly, though, there was a strong rationalist impulse during the founding period, and many of the delegates to the Constitutional Convention were invested in a rationalist sort of theism, if not outright deism. This was all well and good, and might have remained so except that the French Revolution occurred, and soon religious ideas that had been widely embraced by the American founders were widely associated with atheism and violence and the extremes of the Terror in France.

In 1800, when Thomas Jefferson ran for president, he was still clearly associated with the French deistic tradition. He had been ambassador to France before the Revolution, he had witnessed its early stages firsthand, and he remained quite sympathetic to its goals. Supporters of John Adams therefore accused Jefferson of being an atheist and an infidel because of these sympathies. Even after he won the election, Jefferson’s supporters worked hard to dissociate him from atheism and to claim, instead, that he was a Christian. So the French Revolution cast a really phenomenal shadow across American society. Paired with the Second Great Awakening, which occurred almost simultaneously, it helped virtually to extinguish deistic thought in America. It’s a turning point. I’m not claiming that America would have been a more secular nation if not for the French Revolution, but it may well have been a more skeptical nation.

R&P: The phrase “a wall of separation” between church and state is traceable to Jefferson’s “Letter to the Danbury Baptists.” How important is that document to church-state jurisprudence in the U.S.?

SKG: It’s an interesting artifact that I think has taken on more significance than was intended by its author. Clearly Jefferson wrote the letter for public distribution. Because his religious views had been such an object of speculation and criticism, he wanted to state his position publicly and he seized on this congratulatory letter from the Danbury Baptist Association as an opportunity to do that. Interestingly, it’s the only recorded instance, that we know of, in which Jefferson used the phrase “wall of separation.” James Madison had used variations of that phrase five or six times, but clearly Jefferson is the one who has come to be associated with it. Again, the metaphor of a wall predates Jefferson. Whig theorists talked about walls, John Locke wrote about walls, barriers, and separations in his “Letter on Toleration.” Anglican apologist Richard Hooker had written about a wall of separation back in the seventeenth century. The image is not at all unique to Jefferson, but his particular usage has achieved an outsized historical significance. It really wasn’t until 1879, when the Supreme Court first weighed in on a church-state separation case, that Jefferson was formally credited with the idea, and that association was solidified by the Court in 1947.

R&P: Was popular opinion about church-state relations in the nineteenth century at all dependent on which church was being considered? Did Catholics, Jews, and Mormons enjoy the same rights and protections claimed by Protestants?

SKG: Protestants were clearly the major proponents. Then you have the super Protestants, the Nativists, who used it to endorse their nativist, anti-Catholic agenda. There were few in the Catholic community who came out in favor of separation, probably because of the state of Catholic doctrine at that time, which was really more focused on what was happening in Europe than in America. It wasn’t until the end of the nineteenth century that some Catholic figures, such as Bishop Ireland, started to support separation of church and state.

Without a doubt, the church-state arrangement in the United States favored Protestantism over Catholicism, Judaism, Mormonism, etc. But it’s always been a work in progress. It’s an evolution. It wasn’t until about the middle of the twentieth century that some of these traditions began to achieve something approaching religious equality in the United States. And that process continues.

R&P: You write that, in the first half of the twentieth century, the Jehovah’s Witnesses proved uniquely important to the Supreme Court’s handling of church-state questions. Why is that?

SKG: Jehovah’s Witnesses, as a result of a theological outlook that views the larger society as sinful, were poised as a sort of separatist group. They saw that certain regulations were inhibiting their ability to proselytize, and, being somewhat of a litigious group, they decided to litigate matters that could potentially have applied to any number of religious groups, but most specifically applied to them. They could be confrontational, a bit disruptive, and consequently, they ended up being responsible for establishing a lot of the stronger free speech and free exercise principles that continue to abide today.

R&P: I want to ask about a pair of Supreme Court rulings that loom especially large in the book, starting with the 1947 decision that you’ve referenced a couple of times today. Why was Everson v. Board of Education so important?

SKG: It was important, first of all, because it concerned the modern Court—that is, the post-New-Deal Court that law scholars identify as the start of modern jurisprudence. But more than that, in Everson, the Court first formally incorporated, through the due process clause of the Fourteenth Amendment, the idea of non-establishment, meaning that the states could not set up their own religious establishments. It was also important that the Court tried to draw a fine line that would allow religious communities to participate in social welfare and benefits, but nothing more than that; nothing that would entail promoting, assisting, or financing religion. This decision formally established the separation of church and state as the controlling principle.

R&P: What about the 1962 ruling in Engel v. Vitale?

SKG: The Engel case and, a year later, the Schempp case were significant because, by regulating prayer and Bible-reading in the public schools, they brought a new culture war resonance to church-state jurisprudence. There was a belief at the time that you could have nonsectarian religious exercises that would be acceptable to all faith communities. So long as you did not advance any one particular theological perspective, you could always find a lowest common denominator. In fact, that’s exactly what the Engel case dealt with. The New York Board of Regents had thought that they could write a prayer that would be palatable to all religious communities. It was the most generic, watered-down prayer you’d ever want to hear. But still, the Court reached out and took that case to make a point—to make the point that the separation of church and state applies not just to funding questions, but to the government sponsorship of even the mildest form of religious expression. It was a very controversial case at the time.

I point out in the book that, by the time of the Engel and Schempp decisions, only about 40 percent of the nation’s public schools had a form of organized prayer or Bible-reading. So the Court was not getting ahead of itself or ahead of the culture. But it was still a shock that they would issue this ruling, and there was massive resistance for years and even decades after. I grew up in Texas, and we continued to have prayer and Bible-reading over the public address system when I was in high school in the mid-70s. Before I came to Willamette, the last case I helped litigate was a prayer case out of Louisiana in 2001. We still have many people who assign immense cultural significance to these cases.

R&P: Looking back over this history, and given your concerns about the present Court, do you see church-state separation proceeding on a particular trajectory? Do you have any predictions about its status going forward?

SKG: It’s always dangerous to make predictions, but I think we do see a trend here. The Court seems to be moving toward what we might call “one-sided separation,” committed mostly just to protecting religious communities against government regulation. We saw a bit of this during the Covid crisis, over whether religious communities would be subject to social gathering restrictions. Initially the Court was divided, but the composition changed with the addition of Justice Barrett, and the exemptions were then granted. That’s a form of separation—when religious communities are not subject to certain neutral regulations—and that part seems safe.

The other part seems very much in decline. That deals with the question of whether the government can provide affirmative support for religion through funding, etc. Recent decisions have endorsed such support and argued, in fact, that to deny it is to discriminate against religion. Consequently, I suspect James Madison has been rolling over in his grave. When it comes to government support of religion, religious expression the public square, I suspect we are going to see a very low and broken wall going forward. The Court recently accepted a case out of New Jersey dealing with the question of whether a high school football coach can go out onto the field after a game and kneel and lead players in prayer, or whether that is something the school district has the ability to prohibit. At present, they do, but my guess is that the Court would not have taken the case unless they wanted to make a change in the jurisprudence. And I predict they will.