I first encountered Roy Moore in 2002 in a Montgomery, Ala., courtroom, where I was an expert witness on the separation of church and state in what came to be known as the Alabama Ten Commandments case.

Moore, then the state’s chief justice, was the defendant. He had installed a granite block emblazoned with the Ten Commandments in the Rotunda of Montgomery’s Judicial Building, declared that the event marked “the restoration of the moral foundation of law to our people and the return to the knowledge of God in our land,” and then refused to allow any other religious representations in that public space.

“Roy’s Rock” clearly violated the establishment clause of the First Amendment, and Moore was being sued for so blatantly flouting the Constitution. He was silent that day in the courtroom, but he had already made a great deal of noise about the United States being a Christian nation. One of his arguments was that the founders were aware of no religion other than Christianity, therefore the First Amendment gave only Christians the right to free exercise.

That statement, of course, was demonstrably, ridiculously false. But that’s Roy Moore. The Republican Senate nominee has fashioned an entire career out of subterfuge and self-misrepresentation — as a constitutional authority, as a Baptist and as a spokesman for evangelical values. The recent allegations of sexual misconduct, together with his many specious statements through the years — that the First Amendment guarantees religious freedom only for Christians, for example, or that many U.S. communities stagger under the burden of Islamic Sharia law — underscore both his hypocrisy and his tenuous grasp of reality.

In 2004, after Moore was unseated for refusing to obey a court order to remove his Ten Commandments monument and was touring as a kind of full-time martyr for the religious right, I visited him in Montgomery with students from the Columbia Graduate School of Journalism. Moore launched into his riff about how the founders intended Christianity as the only constitutionally protected religion because they knew nothing else.

(The founders were most certainly aware of Jews and Muslims, who appear in the writings of Thomas Jefferson and in the Treaty of Tripoli as “Mussulmen,” the French term. That same treaty, negotiated by the John Adams administration and ratified unanimously in 1797 by the Senate, states that “the United States of America is not, in any sense, founded on the Christian religion.”)

I decided to play along. By Moore’s logic, I suggested, another clause of the First Amendment, freedom of the press, applied only to newspapers and not to other media because the founders had no knowledge of radio, television or the internet. Moore, rarely at a loss for words, was stumped for a moment, but he quickly resumed his bluster.

Aside from boasts about his constitutional expertise, Moore also asserts that he is a Baptist. (He is a member of First Baptist Church in Gallant, Ala.) Once again, his behavior belies that claim.

The Baptist tradition in America is marked by two characteristics. The first is that only adults and older children, not babies, may be baptized. The second is a belief in liberty of conscience and the separation of church and state, which grew in part out of Baptists’ persecution as a minority in early America.

It was Roger Williams, a dissident Puritan who fled to what is now Rhode Island and became the founder of the Baptist tradition in America, who advocated the separation of the “garden of the church” from the “wilderness of the world” by means of a “wall of separation.” In 1802, Jefferson used the same metaphor to summarize the First Amendment while writing to the Baptists of Danbury, Connecticut.

For Williams and his contemporaries, the “wilderness” was a place of darkness where evil lurked. When Williams talked about a wall of separation to protect the garden from the wilderness, his concern was that faith’s integrity would be compromised by too close an association with the state.

For more than three centuries — at least until the 1979 conservative takeover of the Southern Baptist Convention — Baptists patrolled the wall of separation between church and state. Speaking at a 1920 rally on the steps of the U.S. Capitol, Baptist theologian George Washington Truett proudly declared that the separation of church and state was “preeminently a Baptist achievement” and said that “religion must be forever voluntary and uncoerced, and that it is not the prerogative of any power, whether civil or ecclesiastical, to compel men to conform to any religious creed or form of worship.” Truett concluded that Christianity “needs no prop of any kind from any worldly source” and that any such support is a “millstone hanged about its neck.”

That washing-machine-size rock Moore unveiled in Alabama was a 5,280-pound millstone. No one even dimly aware of Baptist heritage would tolerate such chicanery because the confluence of church and state, as Williams warned, diminishes the faith and opens it to fetishization and trivialization.

Finally, Moore claims to represent “family values” and, more broadly, evangelical Christian values. Aside from the disquieting specter of a 30-something Moore trolling shopping malls for teenage dates, Moore does not represent the evangelical movement he claims to herald. Historically, evangelicalism stood for people on the margins, those Jesus called “the least of these.” Evangelicals in the 19th century advocated public education so children from less-affluent families could toe the first rungs of the ladder toward socioeconomic stability. They worked for prison reform and the abolition of slavery. They advocated equal rights, including voting rights, for women and the rights of workers to organize.

The agenda of 19th- and early-20th-century evangelicals is a far cry from that of Moore and the religious right. I leave it to others to determine which version of “evangelical values” better comports with the words of Jesus, who instructed his followers to visit the prisoners, feed the hungry, welcome the stranger and care for the needy.

The image that Moore has tried to project over the course of his career — as a constitutional authority, a Baptist and a representative of evangelical values — is false, even fraudulent. The voters of Alabama have the opportunity to unmask him as the impostor he is.

Randall Ballmer, an expert witness in the Alabama Ten Commandments case, is the John Phillips professor in religion at Dartmouth College and author of “Redeemer: The Life of Jimmy Carter.”