Politicians today can still make reference to Christ in official speeches. Even Clinton did that.
But when it came to the document that actually created this nation - the Constitution - they kept God and Christ out of it. Why do you suppose that was?
They kind of gave it away in the First Amendment, they did not want the Federal Government establishing a religion. But that has been twisted to the point where a student goes to jail if they say the word Jesus in a Graduation Speech. How twisted is that since the very same Constitution grants freedom of religious expression. Current case law on this subject is preverted beyond repair.