Of the many influences that shaped the American concept of liberty, the first and most formative was faith. More than anything else, religion formed the backbone of colonial culture and defined its moral horizon.

This religious character was largely a product of the fact that many came to the New World in search of religious liberty—to freely practice and spread their faith.

As a whole, America’s Founders were strongly religious. Thanksgiving proclamations, as official statements of the American president, underscore the Founders’ faith. Some were more traditional, such as John Jay and John Witherspoon. Some were more skeptical of religious institutions and doctrines, such as Thomas Paine and Thomas Jefferson.

But the vast majority of the Founders were firmly in the mainstream of religious belief. They understood God as having created man with an immortal soul, as actively involved in human affairs and as “the Supreme Judge of the world”—in the words of the Declaration of Independence.

The day after approving the First Amendment to the Constitution and its protections of religious liberty, Congress called upon the president to “recommend to the people of the United States a day of public thanksgiving and prayer, to be observed by acknowledging, with grateful hearts, the many signal favors of Almighty God.”

President George Washington responded by proclaiming Nov. 26, 1789 the first official Thanksgiving. He noted:

It is the duty of all nations to acknowledge the providence of Almighty God, to obey his will, to be grateful for his benefits, and humbly implore his protection and favor.”

Even the deists among the Founders—and it is by no means the case that they were mostly deists, as some have claimed—held that God created the world and determined the rules of human action.

Wrote Paine:

It is a fool only, and not the philosopher, nor even the prudent man, that will live as if there were no God.”

In 1620, more than 150 years before Washington’s first Thanksgiving proclamation, a small group of pilgrims granted land by King James arrived in what is now New England. They wrote out the Mayflower Compact creating their own political community “for the Glory of God and advancement of the Christian Faith and Honour of our King and Country.” This was, in essence, a social contract to form a body politic for the sake of survival.

The Puritans came to America believing “their errand was not a mere scouting expedition: it was an essential maneuver in the drama of Christendom,” writes Perry Miller, pre-eminent historian of the subject. “These Puritans did not flee to America; they went in order to work out that complete reformation which was not yet accomplished in England and Europe.”

The British colonists were overwhelmingly Christian and overwhelmingly Protestant. Congregationalists dominated New England. New York had more Presbyterian and Dutch Reformed churches, along with the Church of England in lower counties. The South was largely Anglican, with some Presbyterian, Quaker and Baptist populations. The Baptists took a much more visible role, particularly in the Carolinas, in the mid-1700s.

During the early decades of the 18th century, the main churches grew at a rapid and astonishing rate, according to research by James Hutson of the Library of Congress. This growth was fueled in large part by the Great Awakening, the religious revival of the 1730s and 1740s, but it continued. Throughout the 1770s, some 70 percent to 80 percent of the population attended church on a regular basis.

One can speculate about the details of each Founder’s faith. But we know the Founders as a whole took religious beliefs seriously and understood religion, Christianity in particular, was a necessary component of republican government.

That there are laws of God that exist prior to, outside of and above the laws of the state necessarily means the laws of the state are limited and controlled by a higher or transpolitical authority. Take the injunction in the Bible to “render unto Caesar the things which are Caesar’s, and unto God the things that are God’s” (Matthew 22:21). In other words, although man has responsibilities to legitimate government authority, the state must not negate or replace man’s responsibilities to God.

The distinction demanded a space for other institutions—church and religious communities, families and tribes—to exist and flourish. The idea of human dignity, that we are created in the image of God, forms the theological underpinning of human nature and human equality—core principles of liberty.

The belief that all men are sinners is the theological equivalent of the commonsense observation that human beings are drawn to their passions and prone to be selfish. It also informs the political idea that no one is to be trusted with absolute power. At the same time, the idea that all are redeemable—that there is a divine spark in each person, as a young George Washington wrote in his childhood copybook—grounds the belief that all can govern themselves and are capable of justice and benevolence.

These concepts in turn became crucial to the beginnings of liberty in America and creation of conditions favoring a yearning not only for self-government but for limited constitutional government. And for all of this we can give thanks.

Note: Matthew Spalding is director of The Heritage Foundation’s Kenneth B. Simon Center for American Studies. This post is excerpted from his new book, “We Still Hold These Truths: Rediscovering Our Principles, Reclaiming Our Future” (ISI).