"I disagree with the idea that God and Christianity has no place in the formation of morals in the US."
That's your mistake then, since I said nothing of the kind.
I did say that the impetus toward life and procreation, and away from death and decay, is more or less universal. There are exceptions. We recognize those exceptions as being wrong, perverse, bizarre, etc.
Religions generally support the articulation of a positive social morality, but all (OK most) are a priori based on the notion that the creation and enhancement of life is fundamental.
I guess I have to turn this around: do you think there is no universal morality outside of Christianity?
Of course there is morality outside of Christianity.
There is no "universal" morality in the sense that all peoples/societies/religions agree on all moral issues.