No matter how noble a nation, it is held together with violence. No matter how charitable, that nation has boundaries beyond which its affections weaken, or turn to hate. No matter how orthodox a nation, it has people who believe differently or do not believe at all.
Separation of church and state is a principle that protects us all. It protects citizens who wish to believe differently, but it also prevents the word “Christian” from being applied to groups that have little or no allegiance to what Jesus actually taught. A nation that turned the other cheek, shared with all in need, and saw every human as a brother or sister would not long exist as a sovereign nation.
The people we call our “founders” did not come to this continent to start a Christian nation. Many of them came to escape from Christian nations elsewhere. There was a struggle to protect the U.S. Constitution from any mention of the Christian religion. There have been repeated efforts to insert sectarian Christian wording into the text, but saner heads have always prevailed because people remembered that after you have chosen one religion over the rest, the next step is to fight over who’s is the one correct version of that religion.