Governor Romney is starting to open up about his religion, the Associated Press is reporting on the eve of the Republican convention at Tampa, and one of the things we are wondering is whether he will finish the story about Reverend Duche. He alluded to Reverend Duche four years ago when he made his big speech about his Mormon religion. That was at Texas, the state where John F. Kennedy made his speech seeking to put to rest concerns about his Catholicism. As it happens the Sun has no worries about Mr. Romney’s Mormonism. The way Mr. Romney told the story of Duche, though, is incomplete. It deserves to be told in full.

“Recall the early days of the First Continental Congress in Philadelphia, during the fall of 1774,” Mr. Romney said four years ago. “With Boston occupied by British troops, there were rumors of imminent hostilities and fears of an impending war. In this time of peril, someone suggested that they pray. But there were objections. They were too divided in religious sentiments, what with Episcopalians and Quakers, Anabaptists and Congregationalists, Presbyterians and Catholics. Then Sam Adams rose, and said he would hear a prayer from anyone of piety and good character, as long as they were a patriot.”

“And so,” Mr. Romney said, “together they prayed, and together they fought, and together, by the grace of God, they founded this great nation.” Which is all true, and appropriate, insofar as it goes. But there is more to the story, as we noted in an editorial in December 2007. For the name of the man who offered the prayer for the revolution was the Reverend Jacob Duche, an Anglican minister who was the first chaplain of the Continental Congress. Mr. Romney didn’t mention his name, but Duche was brought to our attention at the time of Mr. Romney’s speech by Ira Stoll, who was then managing editor of the Sun and one of Samuel Adams’s biographers. The story of Reverend Duche turns out to be a cautionary tale for those who would attach too much to the virtue of piety.

After the revolutionary war got under way, the fight proved far more difficult than that for which Reverend Duche had prayed. The reverend ended up sending to George Washington, then camped at Valley Forge, a letter calling on the revolutionary commander to lay down his arms and seek a peaceful settlement with the British. “How unequal the contest!,” he wailed. “How fruitless the expense of blood! Under so many discouraging circumstances, can virtue, can honor, can the love of your country, prompt you to proceed?”

Then the ink of treason. “[R]epresent to Congress,” Duche implored Washington, “the indispensable necessity of rescinding the hasty and ill-advised declaration of independency. Recommend, and you have an undoubted right to recommend, an immediate cessation of hostilities.” The letter is a long one, as the reverend went on and on, trying to disguise his perfidy in high-minded sentiments. “I love my country; I love you,” he lied. “But to the love of truth, the love of peace, and the love of God, I hope I should be enabled, if called upon to the trial, to sacrifice every other inferior love.”

Washington, even in the blood-soaked snow of Valley Forge, knew instantly what he’d just read. He sent it immediately to the Congress, with a note saying he’d that if he’d had in advance any idea of the contents of Duche’s letter he’d have returned it unopened. Duche was tried and convicted of treason against Pennsylvania and fled to England, where he spent the war in the bosom of our enemy. He eventually returned to America, where he died in a disgrace that — if Mr. Romney is going to use Duche’s tale at all — deserves, particularly in a time of war, to be brought into sharp relief.

The most emphatic sentence in the entire United States Constitution, after all, is the prohibition — “No . . . ever . . . any” — on religious tests for public office. Mr. Romney has been “long silent on his Mormonism,” as one headline put it over an AP story reporting that religion and involvement in the Church of Jesus Christ of Latter-day Saints have “shaped every aspect of Romney’s life, from his family to his decades in private business and his political career.” It is a wonderful thing that the man the Republicans are about to nominate for president is prepared to share his spiritual world with his countrymen. His spirit is inspiring. But the Founders of America understood the story of Reverend Duche. In the end, it is the not piety but the patriotism. We don’t suggest that Mr. Romney lacks for either. But it is the patriotism on which presidents are tested.