Wrong

I get tired of hearing the argument that the founding fathers wished for the "separation of church and state". 

This phrase never appears in the Constitution, nor in the Declaration, nor even in the Federalist Papers.

Not even once. Despite what people parrot, it is not used in any of these documents... It is inferred in the First Amendment, "Congress shall make no law respecting an establishment of religion,or prohibiting the free exercise thereof..." but that phrase "separation"is not used, and the First is not meant for that. It says clearly what it says. Nor does Article 6 say anything about the "separation of church and state", but rather that "no religious test shall ever be required as a qualification to hold any office or public trust..." Not quite the same thing as "separation of church and state".

Even the courts do not always agree that the phrase by Jefferson has anything to do with, or may be substituted for the First Amendment.

Those who use the phrase "separation of church and state" are misquoting Thomas Jefferson, and are demonstrating their ignorance. Parroting a phrase that hey heard from someone else, with no knowledge of where it came from, the context in which it was used, or what was meant by it.

Don't believe me? Look it up yourself. I'm not gonna bother to give you a link.

But stop using the phrase where it doesn't belong, and stop saying that it is in any of the documents that founded this country, or that that phrase has anything to do with the rules that govern our country.