The idea of a Christian America means different things to different people. Pollsters have found a wide circle of Americans who hold general God-and-country sentiments.
But within that is a smaller, hardcore group who also check other boxes in surveys — such as that the U.S. Constitution was inspired by God and that the federal government should declare the U.S. a Christian nation, advocate Christian values or stop enforcing the separation of church and state.
For those embracing that package of beliefs, it’s more likely they’ll have unfavorable views toward immigrants, dismiss or downplay the impact of anti-Black discrimination and believe Trump was a good or great president, according to a 2021 Pew Research Center survey.
I'm not defending the argument below. It is patently stupid.
I have heard people make the argument that the founders didn't expect non-christian religions to become prominent in the US. That they thought they were only protecting the right of people to practice any kind of christianity they want to practice.
They think that the founders didn't have enough forethought to realize that people of other faiths might migrate to the US or even the presence to realize that there were already non-christian faiths being practiced in the colonies.