In 1776, long-persecuted Baptists hoped that the American Revolution would not only secure America’s liberty, but bring about full religious freedom. Thomas Jefferson and James Madison became their key allies in fulfilling that ambition. Jefferson’s collaboration with the Bible-believing Baptists was spiritually ironic. He remained relatively quiet about his religious skepticism during his political career, but in truth Jefferson did not believe in the resurrection of Christ or that Jesus was the Son of God. Nevertheless, in 1802 President Jefferson appealed for religious liberty in a letter that has become known as the “wall of separation” letter.

“I contemplate with sovereign reverence that act of the whole American people which declared that their legislature should ‘make no law respecting an establishment of religion, or prohibiting the free exercise thereof,’ thus building a wall of separation between church and state,” Jefferson wrote. Scholars and jurists have endlessly debated and dissected the meaning of Jefferson’s wall of separation.

In 1998, the Library of Congress even brought in FBI document analysts to reveal what Jefferson had written in an earlier draft. But the recipients of the letter are interesting as well: Jefferson, the deist, was writing to some of his staunchest supporters, the Baptists of Danbury, Connecticut. These evangelical dissenters still languished under an official state denomination, eleven years after the First Amendment’s ban on “an establishment of religion” and guarantee of the “free exercise of religion.” Jefferson’s letter demonstrated the partnership between skeptical or liberal Christian politicians, and legions of Baptists, in the cause of religious liberty. This alliance helped score the Baptists’ most significant success of the Revolution, the widespread disestablishment of state churches.

The Danbury Baptist Association was founded in 1790 as an advisory council for Baptist churches in western Connecticut. From the start, it identified “full gospel liberty” as one of its core values. But it found gospel liberty difficult to achieve because of the state’s continuing official support for the Congregationalist Church. Dissenters could file certificates to receive exemption from religious taxes, but in 1791 the state tightened the standards to qualify for such exemptions. Baptists thought that even filing the certificates was an obnoxious requirement and an intrusion of the state into the realm of the spirit.

Baptists across America rejoiced when Thomas Jefferson was elected president, because they saw Jefferson as the great champion of religious liberty, especially in light of his 1786 Bill for Establishing Religious Freedom in Virginia. The Danbury Baptists wrote to Jefferson in late 1801 and congratulated him on what they saw as a providential victory over John Adams: “We have reason to believe that America’s God has raised you up to fill the chair of state out of that good will which he bears to the millions which you preside over.” They knew that Jefferson could not alter state laws by fiat, but they hoped that his commitment to religious liberty would, “like the radiant beams of the sun . . . shine and prevail through these states and all the world till hierarchy and tyranny be destroyed from the earth.” To them, one of God’s ultimate purposes for the War of Independence was to bring about gospel liberty, and Jefferson’s election was the next milestone in that process.

The Republican Jefferson was delighted to have such allies in predominantly Federalist New England, and he wanted his response to the letter to sow “useful truths and principles among the people” regarding religious liberty. During the 1800 campaign, Jefferson’s opponents had attacked him as a heretic, and as president he was already coming under criticism for failing, unlike his predecessors, to declare public days of prayer and fasting. He wanted to clarify that, just like the Baptists, he really did support the flourishing of religion in America. To Jefferson, the best way to support religion was to grant all citizens religious liberty. This was the ingenious compromise of the First Amendment’s religion clauses: the free exercise of religion required the absence of a national church.

In the carefully drafted letter, Jefferson wrote that because he believed “that religion is a matter which lies solely between man and his God, that he owes account to none other for his faith or his worship, [and] that the legitimate powers of government reach actions only, and not opinions,” he treasured the separation of church and state enshrined in the First Amendment. He looked forward to the “progress of those sentiments” at the state level, too. But he and the Baptists would have to wait until 1818 for Connecticut to disestablish the Congregationalist Church.

Beginning with the Supreme Court’s decision in Everson v. Board of Education (1947), jurists have used Jefferson’s metaphor as a key gloss for interpreting the First Amendment’s establishment clause. (They have also “incorporated” the establishment clause so that it applies to the states as well as the national government.) In Everson, Justice Hugo Black, an Alabaman and lapsed Baptist, cited Jefferson’s letter and declared that the First Amendment’s wall of separation must be “high and impregnable.” But is a modern strict separationist view of church-state relations what the Danbury Baptists (or Jefferson) wanted? Did they wish for government to have no connection whatsoever with religion?

A clue to the answer came two days after Jefferson sent the “wall of separation” letter. That Sunday, an old ally of Jefferson’s in the fight for religious liberty, Elder John Leland, preached before a joint session of Congress, with the president in attendance. Leland explicated the biblical text “Behold a greater [one] than Solomon is here.” An incredulous Federalist congressman complained in his diary that “such a farrago, bawled with stunning voice, horrid tone, frightful grimaces, and extravagant gestures, . . .was never heard by any decent auditory before.” Whatever else the wall metaphor meant in 1802, it permitted a Baptist pastor to preach before Congress. That remarkable moment, capping the dissenters’ celebration of Jefferson’s election, illuminated the alliance between evangelical Baptists and skeptics such as Jefferson that, in time, won disestablishment across the whole nation. That victory was the most important religious outcome of the American Revolution.