Benjamin Franklin grew up in a devout Puritan family in colonial Boston, but by his teen years he began to doubt key aspects of his parents’ Calvinist faith. (Philadelphia Museum of Art/AP)

Today marks the 230th anniversary of one of the most intriguing episodes of the Constitutional Convention. On that day in 1787, the 81-year-old Benjamin Franklin, famously known as a deist, proposed that the convention open its sessions with prayer. Deists, who believe God created the universe but remains apart from it, aren’t supposed to believe in prayer or that God intervenes in history.

But the puzzling moment over prayer tells us a great deal about Franklin himself and about the role of faith in the nation’s founding. There was a lot more to Franklin’s religion than his self-description as a deist. In fact, Franklin was the pioneer of a uniquely American kind of faith, one which touted the benevolent effects of faith even as it jettisoned virtually all theological beliefs.

During the convention’s first month, the delegates were bogged down in intractable debates between the large and small states, and the free and slave states. The delegates’ inability to agree on issues such as representation in Congress illustrated the “imperfection of human understanding,” Franklin observed in his papers.

“In this Situation of this Assembly, groping, as it were, in the dark, to find Political Truth,” Franklin asked, “how has it happened, sir, that we have not, hitherto once thought of humbly applying to the father of lights to illuminate our understandings?” During the American Revolution, the patriots had seen repeated instances of God intervening in their favor. “And have we now forgotten that powerful friend?” Franklin wondered.

Franklin cited his age and experience as he defended his belief in prayer and the Providence of God. “I have lived, sir, a long time; and the longer I live, the more convincing proofs I see of this Truth, that God governs in the Affairs of Men!”

This was a doubly strange proposal coming from Franklin. Since he was arguably the representative figure of the American Enlightenment, we might imagine that Franklin had supreme confidence in “human understanding” to fix political problems. Moreover, Franklin told us in his autobiography that he was a “thorough deist.”

Franklin adhered to a religion that we might call doctrineless, moralized Christianity. This kind of faith suggests that what we believe about God is not as important as living a life of love and significance. Franklin grew up in a devout Puritan family in colonial Boston, but by his teen years the bookish boy began to doubt key aspects of his parents’ Calvinist faith. Abandoning Christianity altogether, however, was not a realistic option for someone as immersed as Franklin in the Bible’s precepts and the habits of faith.

Although Franklin did at times toy with some radical anti-Christian beliefs, he settled on the conviction that Christianity was useful because of the way it fostered virtue. Franklin wearied of how colonial Americans incessantly fought about theological minutiae. But he still believed that Christianity represented a preeminent resource for benevolence and charity, qualities he considered essential to any worthwhile religion.

Franklin, John Adams and Thomas Jefferson all doubted some fundamental tenets of the Protestant faith. These could include salvation by God’s grace alone, the divinity of Jesus, or God’s Trinitarian nature. But leading patriots agreed that the new American republic depended upon having a virtuous citizenry. Although some elites might employ education to develop moral fortitude, the founders believed that average Americans needed religion for the inspiration to do good.

Franklin saw the convention’s impasse over representation in Congress as a perfect example of how rational deliberation alone failed to foster compromise for the greater good. But prayer could remind the delegates of their need for divine assistance and national unity.

Franklin was exasperated when the convention declined to hire a chaplain to lead the prayers. But perhaps the speech still had a unifying effect, as Franklin later helped to craft the “Great Compromise” over representation in the House and Senate, arguably the critical agreement of the whole convention.

In pioneering this doctrineless, moralized Christianity, Franklin was helping to develop one of the most common forms of spirituality in modern America. Adherence to specific beliefs and congregations is slipping in many sectors of America today, but Americans remain an overwhelmingly theistic people. Self-help celebrities and writers from Oprah Winfrey to Steven Covey reach audiences in the hundreds of millions with their quasi-religious messages about living a life of maximal goodness and significance. Even popular preachers like Houston megachurch pastor Joel Osteen downplay doctrine in favor of practical sermons and books on living “your best life now.”

Franklin’s Christian friends and relatives were always worried that the great printer, scientist and diplomat might be gaining the world but losing his soul. Traditional Christians today would likewise argue that authentic faith is based upon true beliefs about God, Jesus and the Bible. But the “deist” Franklin was convinced that in crafting a doctrineless, moralized Christianity, he was redeeming the best of traditional religion by channeling it toward the ideals of love and charity.

Thomas S. Kidd is the author of “Benjamin Franklin: The Religious Life of a Founding Father” (Yale University Press, 2017).