Some time ago I assembled a few earlier threads to answer a similar question. I can repost them here below:

You can read here about how the USA became more religious in the decades after its founding than it had been before, as explained by u/uncovered-history and based on some earlier answers. There is also this thread by u/ekmetzger which discusses the Founding Fathers' personal religious beliefs, and this one by u/TheExquisiteCorpse which focuses on their views on Islam and Muslims