Summary: The relationship between Christianity and the founding of the United States is a complicated matter.
As I was finishing up In the Beginning Was the Word: The Bible in American Public Life 1492-1783, I picked up God of Liberty. Thomas Kidd’s history is well known and spoken of well by Mark Noll and many others. God of Liberty was the historical overview that I needed after the very particular history of the use of scripture.
The role of Christian faith in the founding of the United States is fraught matter. All sides have reasons for why it matters (often more about current events than historical accuracy.) And because there are a large number of founding fathers, pretty much anyone can find support for their position by proof texting a few pamphlets or speeches or sermons.
God of Liberty does a good job at showing the complication of any particular position. Christian faith was important to many in the colonies, both as a reason for coming to the colonies and as a reason for breaking away from Britain. But separation of Church and state, at least in it early incarnations, was also important in how the country was organized during and immediately after the revolution.
England had a state church, so many of the more radical revolutionaries were against state churches as a concept. But many of the colonies already had a state church with their own constituencies and theological reasonings.
As Noll illustrated, many of the ways that scripture (and Christianity) were used in political rhetoric were more about referencing ideas than referencing God or scripture or identifying directly with orthodox Christian faith.
There really were a lot of deists among the founding fathers. But there were also more than a few devout Christians, and more than a few politicians willing to put their public devotion on display.
I was more interested in the religious parts of the political history than the actual religious history sections because I have a pretty good background on the great awakenings and the founding of Baptists in the US and some other fairly common topics in history of American Evangelicalism. But if you are looking for a history of early Evangelicalism this isn’t a bad place to start.
This along with Noll’s history and Ron Chernow’s biography of Hamilton are three back to back books on early American history. All three hit very different areas of history and are all well written. This is an area that has many good books.