See the Establishment Clause of the First Amendment.
"Congress shall make no law respecting an establishment of religion, or prohibiting the free exercise thereof"?
This is not an "establishment clause" insofar as people are wont to suggest it is. You would have been better off invoking the "religious test" portion of the US Constitution, but that wouldn't have actually helped your argument either.
According to the original meaning at the time, it meant that there would be no Officially Sanctioned State Religion, insofar as the citizenry would be required to be a member of it or pay tithes to it, or promulgate it's doctrine. It was a necessary step to prevent the blowing apart of the coalition of states that had different official state religions.
That the Nation was going to be explicitly Christian was a given, and implicit in all the founding documents and even in the US Constitution itself, where it exempts the President from working on Sundays and acknowledges Jesus Christ as "Our Lord" at the end.
People keep trying to apply modern feelings to it which were only put into place in the 1940s, after all the Roosevelt appointed Kook Judges had achieved maximum kookery on the Supreme Court.
See Everson v. Board of Education
See Lemon v. Kurtzmann
Garbage in, garbage out. Court rulings after 1940 are just legal sounding gibberish. The 14th amendment was created to protect the rights of freed slaves, not abolish religion in the States. That is a a deliberate mis-application of the badly written 14th amendment.
What the 14th amendment was not created to do.
It was not created to make a right to abortion.
It was not created to ban religion.
It was not created to make the children of illegal aliens into citizens.
It was not created to make homosexual acts legal.
It was not created to rewrite the "natural born citizen" clause of the Constitution.
And so forth.
The 14th amendment is the most bastardized and abused amendment in the Constitution, and much of the damage can be attributed to how badly it was written, and how illegally it was passed.