Separationism's decline began some 40 years ago, in response to ecumenicalism, social welfare legislation, and the rehabilitation of the Catholic Church.
Almost every constitutional law scholar—Left, Right, and center—agrees that the U.S. Supreme Court’s Establishment Clause jurisprudence is, to put it kindly, confused. Much of the blame for this mess can be laid at the feet of Everson v. Board of Education, which turns 70 this year.
Justice Hugo Black, who wrote Everson’s majority opinion, and Justice Wiley Rutledge, who wrote the dissent, differed as to the outcome of the case; but Black agreed with Rutledge when the latter declared: “No provision of the Constitution is more closely tied to or given content by its generating history than the religious clause of the First Amendment. It is at once the refined product and the terse summation of that history.”
Since 1947, virtually every Supreme Court justice has embraced this historical approach to interpreting the Establishment Clause. Indeed, judicial liberals have appealed to America’s Founders to shine light on this constitutional provision more often than have judicial conservatives. Unfortunately, the liberals have embraced a faulty historical argument that I refer to as “Everson’s syllogism.” It goes as follows:
The Establishment Clause must be interpreted in light of the Founders’ intent.
Thomas Jefferson and James Madison represent the Founders.
Jefferson and Madison wanted to build a wall of separation between church and state.
Therefore, the Establishment Clause requires a wall of separation between church and state.
In his opinion for the Court, Black made five distinct references each to Jefferson and Madison, but appealed to only one other Founder (Patrick Henry, in his capacity as an attorney in the “Parson’s Cause”). In his dissenting opinion, Rutledge made a whopping 62 distinct historical appeals—including 11 to Thomas Jefferson and 28 to James Madison—to support his conclusion that the Founders desired to erect a high wall of separation between church and state. Lest anyone miss Madison’s significance, Rutledge appended to his opinion the text of the Memorial and Remonstrance (1785).
Everson’s syllogism went largely unchallenged by the Supreme Court until William Rehnquist’s dissenting opinion in Wallace v. Jaffree (1985). Even after this devastating critique, far too many jurists have continued to rely on its faulty historical narrative. Numerous academics and activists have done the same.
The syllogism is flawed at a number of levels. To begin, it is not evident why the Establishment Clause should be interpreted in light of the views of a Founder (Jefferson) who was not even in the country when it was drafted. It is often asserted that members of the first federal Congress were influenced by his Virginia Statute for Religious Liberty, drafted in 1777, but there is virtually no evidence that this was the case. 
Problematic as well (as I have pointed out elsewhere) is that while Jefferson and Madison wanted greater separation between church and state than did most Founders, they had no desire to build the sort of high wall of separation desired by groups such as Protestants and Others United for Separation of Church and State or the American Civil Liberties Union.
Finally, there is no good reason to think that Jefferson’s and Madison’s views on church-state relations were widely accepted. Indeed, in this and many other respects, they were outside the mainstream.
Everson’s syllogism is bad history, and it leads to bad law and public policy. Its logic has been used to restrict, or attempt to restrict, religious liberty. For instance, opponents of religious accommodations for pacifists, equal access, and school vouchers have all contended that statutes designed to protect or promote religious freedom violate the Founders’ commitment to the separation of church and state.
America’s Founders clearly did not want a national church, but they had no desire to remove religion from the public square. They certainly did not intend for the Establishment Clause to limit the ability of legislatures to protect religious liberty or enable parents to send their children to schools of their own choosing.
Our country is far more pluralistic today than it was in the late 18th century, and there are very good reasons for government officials not to favor one religion or denomination over another. But these are questions of civility and prudence that should be addressed by elected officials, not by jurists or advocacy groups who embrace a faulty understanding of the First Amendment’s generating history.
To grasp the Founders’ views of religious liberty and church-state relations, one should consider the words and deeds of more than two men, no matter how influential. To mark Everson’s 70th anniversary, Law and Liberty has asked me to write a series of posts highlighting how different Founders approached these issues. The series will include men such as Roger Sherman, Charles Carroll, Oliver Ellsworth, Benjamin Huntington, Samuel Livermore, Abraham Baldwin, and Fisher Ames, all of whom played a significant role in drafting the First Amendment.
The series will also consider figures such as George Washington, John Adams, George Mason, John Jay, John Marshall, Isaac Backus, John Dickinson, Patrick Henry, John Witherspoon, and Luther Martin. While they were not directly involved in writing this constitutional provision, all participated in the debates of that era over religious liberty and church-state relations. If one is interested in the views of “the Founders,” surely these individuals should be included in the discussion.
Everson’s syllogism has contributed significantly to the Supreme Court’s confused Establishment Clause jurisprudence. It has also been used to threaten what the Founders regularly referred to as the sacred rights of conscience. The posts to follow will hopefully put to rest Everson’s syllogism, provide a more accurate account of the generating history of the First Amendment, and provoke a robust discussion about how religious liberty can best be protected today.
 Rutledge in Everson v. Board of Education 330 U.S. 1 (1947), 33.
 I document the Supreme Court’s use of history in its Religion Clause jurisprudence in “Jeffersonian Walls and Madisonian Lines: The Supreme Court’s Use of History in Religion Clause Cases,” Oregon Law Review 85 (2006), 563-614.
 See Mark David Hall, “Madison’s Memorial and Remonstrance, Jefferson’s Statute for Religious Liberty, and the Creation of the First Amendment,” American Political Thought 3 (Spring 2014), 32-63.