Our country was established on many Christian ideals, no argument from me. I also know many people came here to escape religious persecution.
This is obvious in the first amendment -Congress shall make no law respecting an establishment of religion, or prohibiting the free exercise thereof; or abridging the freedom of speech, or of the press; or the right of the people peaceably to assemble, and to petition the Government for a
redress of grievances.
Several states prohibited the support of religion (though many were Christian and believed others should be as well)
There is no way to be fair to all, if preference is given to only one. It would have been ludacris for people to leave America to avoid persecution (considering that's why they came) and so intelligently they found it wise to do what they had.
Our forefathers were not unreligious, or anti-religious, many quite the contrary. What they were aiming for was tolerance. People, able to be themselves, living with other real people.
Tolerance is what we need to learn.