You are ignoring the history of almost all of the colonial and early states populations went to church. Why are you so adamant about ignoring that history. Only a fraction of the population didn't go to church. That started to change in the 1960s. Today almost half of the population attends church but only a fraction hear the gospel message. The main protestant denominations are secular and the sub denominations and independent churches are the only ones preaching the gospel message. That secularization of denominations started in the 1880s. Gary North wrote the book "Crossed Fingers" documenting the secular takeover of the Presbyterian USA by 1932. Same thing was happening in the other main denominations. Secular ministers wanted access to the churches money. Presbyterian PCA prevents this with the BCO rules about handling money in the denomination. The board of Deacons handles the money. It sets the pay of all employees including the pastor(s). They also decide what committee gets what money they use with the exception of earmarked donations to the church. The pastor(s) is supplied with a relatively small fund for out of pocket mercy giving. For bigger needs the mercy committee decides in consultation with the pastor(s).The U.S. is a secular society and always has been, the country is based on law and with a clear division between church and state.
There is no government mandated religion.
The fact that founding fathers had a religious view, as did some the settlers, does not translate into the United States being a Christian nation.