On 3 January 1797, 214 years ago, Joel Barlow, an American poet pressed into service as the US consul-general in Algiers, drafted and signed the treaty of Tripoli. Its article 11 states: "The government of the United States of America is not, in any sense, founded on the Christian religion." In 1797, to those who had drafted and signed the declaration of independence and the constitution, it seemed a statement of plain truth. American newspapers reprinted the treaty of Tripoli without igniting public debate. The US Senate approved it unanimously and without discussion. President John Adams signed it without comment.

In the past two generations, a "Christian nation" movement in the US has made article 11 of the otherwise-forgotten treaty of Tripoli's an occasional point of debate. In a sense, article 11 is a bit of an enigma. Why was the disavowal of Christianity included in the treaty? Did Barlow intend it to mollify the Bey of Algiers and other Muslim leaders of the Barbary states, whose piracy exerted an expensive toll on US shipping in the Mediterranean? Was it meant to rally European revolutionaries, who had become Barlow's friends and allies? Did it aim to consolidate the authority of Thomas Jefferson and other secularists in America, whose achievements Barlow prized? It is not clear, and Barlow never explained.

It may not be clear why Barlow put article 11 in the treaty of Tripoli, but it is clear that he had once had religion, and lost it. Following his 1778 graduation from Yale, he entered the ministry and, in 1780, became a chaplain in the revolutionary army. In 1784, the Connecticut general assembly even made Barlow the state of Connecticut's official translator of the Book of Psalms. In 1792, however, after four years in London and Paris, he published Advice to the Privileged Orders, a revolutionary work which, basically, offered members of the European aristocracy their lives in exchange for their surrender.

Advice to the Privileged Orders included a polemical attack on religion. "Nations," wrote Barlow, "are cruel in proportion as they are religious." The jury was still out, he wrote, on whether Islam, "the crescent of the east", was infused with "the lust of slaughter", but he insisted it was simply a matter of the historical record that Christianity had "committed greater ravages" than any other religion. "The cross of the west," he wrote, was "the wandering demon of carnage."

In contrast to the militant secularists of today, whose work suggests that ignorance and feeble individual minds lead to religion, Barlow thought that sick societies led to religion. More moderate secularists today are quick to concede the formal beauty or theoretical appeal of religion. Barlow granted no such allowance. Religion is not a good idea that men corrupt, he wrote, rather "men are corrupted by the church".

Barlow thought that a religion or "mode of worship" granted "any preference in the eye of the law" was incompatible with "equal rights". Therein lay the force and the fury that drove the first generation of American secularists. Religion, they insisted, was responsible for inequality. The moment any member of a society is granted "familiar intercourse with God, you launch him into a region of infinities and invisibilities", which alone could obscure the natural equality and brotherhood of all men. The creation of a clerical class, the "giving to one class of men the attributes of God", was the very inception, the root and branch, of inequality. Abolish all legal privileges for religion, Barlow wrote, and you will then begin "to tear the bandage from the eyes of mankind, to break the charm of inequality".

In Advice to the Privileged Orders, which was meant primarily for European readers, Barlow boasted of the historic contribution of the United States to secular government. It was American secularism, he wrote, that made possible, "the continuation of public instruction in the science of liberty and happiness".

Today it would impossible to appoint a man with Barlow's outspoken radical views to a high-level diplomatic post. No doubt, too, that Barlow would be dismayed at how, in the United States, secularism and the fight for equality have parted ways. For him, that was the point.