Thanks for the list of quotes, I'm sure they will come in useful for me.

But I'm asking what actual principles or aspects of our country are unique to Christianity.

Having people, even our Founding Fathers, simply say that the US is founded on Christianity is not giving an answer as to what those principles are.

For instance, you have one who says that religion is a source of morals, thus we need religion. Yet Christianity is not the only religion that people base morals upon.