We are a “Christian” nation when it suits us. This always been the case.
We tend not to pick sides based on religion, but on profit. If the two are in synch, that’s great. If not, we wave the first amendment into battle.
We don’t even bother pretending anymore; we aren’t remotely “Christian”. Iraqi and Syrian Christians can attest to that; we are a post-Christian secular country along the lines of Republican France after the French Revolution.