I have recently read the CPH published book, "The Anonymous God" edited by David Adams and Ken Schurb (that's the Amazon link, the CPH link is here). A colleciton of writings mulling the topic of "civil religion", it was helpful in understanding where we have been, as well as where we are when it comes to the intersection of "government and God" in the U.S.
Here is an interesting article which pertains to the topic. While the article seeks to prove America is a Christian nation by citing references to God in state constitutions, it is an "anonymous God", for I failed to notice any references to JESUS CHRIST therein. For your information:
Here's the article.