I don’t know when it became acceptable for some to espouse that our society is an outgrowth of the Christian faith. It is not a notion that could possibly endure in such a diverse nation.
The closest America ever came to a unification of religion and government was the Pilgrim and Puritan settlements in New England. The strict theocracy lasted about 50 years before it modified to a more secular model. Dissidents like Roger Williams who was banished from Massachusetts in 1636 (16 years after the Pilgrims landed), founded Rhode Island. As the 17th century closed, there was a diminishing influence of any one faith.
In the early colonial days, there were Quakers, Catholics, and Jews who sought refuge in what was to become the United States. The settlers were overwhelmingly Christian and brought with them their faith. But the 18th century had a more nuanced version of what was meant by a Christian nation than many who spout that phrase today.
Many of the Founders were deists. Washington, Franklin, Adams, and Jefferson were the most famous. Deists believe in the moral teachings of Christianity but not in the divinity of Christ. The 18th century was the “Age of Reason” sparked by the French Enlightenment. Thomas Paine wrote a book by that title and argued for rational deism.
They believed that God was a great Clockmaker. He made a perfect universe with all the gears and springs turning in unison. God then stepped back and allowed man to solve his individual and societal problems through the gift of reason. Their enlightened view was that no one religious sect was to be more important than any other.
I am well versed in the teachings of Christianity. For many, those teachings become a bedrock for the development of our morality. I grew up a Catholic and at one point belonged to a Presbyterian Church. Liturgically they are very different, but their underpinnings share many of the same beliefs. The very morality of my belief is summed up in the Gospel of Matthew “Thou shalt love the Lord thy God with all thy heart, and with all thy soul, and with all thy mind. This is the first and great commandment. And the second is like unto it, thou shalt love thy neighbor as thyself (Chapter 22:37–39).” Whether Presbyterian or Catholic, those versus from the Gospel of Matthew are the same.
The United States is not a particularly Christian nation. The Founders had very different ideas than today’s proponents of Christian nationalism. Any nation that was founded on immigration and continues to be composed of immigrants and their decedents can’t have such a narrow definition of nationhood.
Christian nationalism is more about exclusion than inclusion. An “us” against “them” mentality that sets up different classes of people. It is based on a belief that only a chosen few should govern and have political rights. That is everything the Founders were against. There were no religious tests and no established religion written into the Constitution.
Christian nationalism is another way of saying that a pluralistic democracy will have to have too many of the “others” and might eventually exclude me. What will keep Christian nationalists safe is what they fear. That is a nation that allows all a place at the table.