George Washington’s writings have long served as a guide to America’s first president—what he thought, how he made his decisions, even how he felt about his wife.

But when it comes to his personal religious beliefs, Washington seems to have been a closed book—or, at least, unwilling to commit many of his own views to the page. Unlike many of his peers, including Thomas Jefferson, Benjamin Franklin and John Adams, Washington never explicitly laid out his own beliefs—even as he alluded to them in passing on many occasions.

With so few actual accounts to draw from, historians are mostly limited to analyzing what Washington did, to try to understand what he may have believed. The trouble is, even his most straightforward actions can be hard to read and, at times, appear contradictory. The first president encouraged his fellow Americans to show up for worship, for instance, but sometimes struggled to make it to church himself for weeks at a time. For many years, he served as a dedicated vestryman and church warden, but left services instead of taking communion. And while he peppered his writings with references to Providence, there’s comparatively little mention of God or of Jesus Christ.

Scholars and biographers have long puzzled over how to reconcile these inconsistencies. Some argue that he appears to have followed Deism, an 18th-century movement that placed human experience and rationality over religious dogma. Others have suggested he may even have been an atheist, drawing on accounts from Jefferson, who described him as not believing "of that system” of Christianity. Stories of Washington’s prayers, even as they exist, are often unreliable. Original sources for the famous tale of the first president “kneeling” in prayer at Valley Forge have been called into question; several historians have noted that Washington, when he prayed, always remained standing.

What is known is that Washington grew up in the Church of England, then Virginia’s state religion. The great-great grandson of an Anglican pastor, he was baptized as an infant and remained somewhat active in the Anglican church for the rest of his life. But it’s not clear whether he did so out of belief or out of necessity, since religious affiliation was a virtual requirement across many areas of his life. In order to hold office in colonial-era Virginia, for instance, officials had to be affiliated to the state religion, follow its doctrine and avoid disagreeing with it. As a young adult, Washington became a member of the freemasons, a secretive fraternal organization, modeled on Old World guilds, that stressed intellectual, spiritual and moral improvement. The group at that time banned its members from being either “a stupid Atheist nor an irreligious Libertine,” according to its constitution, and required them to adhere to a religion of their choice. He remained a Mason for the rest of his life.

Whatever his own beliefs, Washington seems to have viewed organized religion as a valuable, unifying force in often fractious times. As a military leader in the French and Indian War, he unsuccessfully pushed for a unit chaplain; even when he failed to get one, he encouraged his men to take part in public prayers. Religious beliefs, he argued in his Farewell Address, could help to establish a moral code to help maintain democracy and decorum, even if not everyone believed precisely the same things. The "wisdom of Providence," he declared, "has ordained that men, on the same subjects, shall not always think alike.”

In late 1789, Washington issued what some historians have since described as the first-ever executive order. The last Thursday of November, he said, would be a day of thanksgiving and prayer, marking the end of a brutal Revolutionary War.

His 456-word Thanksgiving Proclamation gives a few clues about how he may have seen a higher power. It was, he wrote, “the duty of all Nations” to acknowledge, obey and be grateful to “Almighty God.” That same God is a “great and glorious Being,” he goes on to explain, and the “beneficent Author of all the good that was, that is, or that will be.”

But historians note that the political context in which Washington gave this proclamation makes it harder to distinguish between what he genuinely believed—and what he thought citizens needed to hear as the war came to a close and the new nation faced its “what next?” moment. The only “favor” he directly encourages Americans to thank God for, for instance, is the “opportunity...to establish a form of government for their safety and happiness.” Later on, he thanks Him for “favorite interpositions of his providence,” essentially chalking up the end of political strife, and his own election as president, to divine intervention.

Invoking divinity may have served as a useful political tool to support the birth of a nation, but there’s good evidence that, if Washington believed anything, it was that American citizens should be free to worship however they pleased. As early as 1775, he pushed for religious plurality, tolerance and freedom, ordering his troops not to burn an anti-Catholic effigy of the Pope on Guy Fawkes Night, out of respect to the Catholic church. Later on, he would oppose committing the state to one religion (the Episcopal church), and he publicly decried a tax that would have supported that church, on the grounds of supporting religious freedom.

On a personal level, Washington took pains to spend time with people of all different religious affiliations, including speaking at synagogues, going to many different kinds of churches and spreading the message that this new country would be against religious persecution in any forms. As he traveled across the country, Washington attended services seemingly indiscriminately at Presbyterian, Quaker, Roman Catholic, Congregationalist, Baptist and Dutch Reformed churches alike. Even when choosing workmen at Mount Vernon in 1784, he was agnostic about their religion, suggesting they could be “Mahometans, Jews, or Christians of any Sect, or they may be Atheists"—so long as they were good at their work.

For the last 25 years of his life, as he sought to manage 13 often recalcitrant colonies, Washington consistently supported the tolerance of different religious traditions, publicly and individually. This, writes historian Mary Thompson, was something he saw as “a unique and basic quality of the new United States.” It was a radical proposition, and one that set the fledgling United States at odds from most other nations.

It may be that we learn the most about Washington’s beliefs by what he doesn’t say—that, in choosing not to promote his own religious creed, he encouraged those around him to respect, engage with and promote the many different faiths of their new American peers.