"Congress shall make no law respecting an establishment of religion, or prohibiting the free exercise thereof"
I witnessed a lie just now. While channel flipping, I caught a preacher talking about the "Wall separating the Church and State" (in the context of a discussion about our schools and government buildings) and how the First Amendment of the United States Constitution does not mention a "wall", a "separation", the "Church" or the "State". Those words themselves do not appear in the First Amendment. So, how is this a lie? Well, yes, there is no mention of a wall. That was a metaphor created to Thomas Jefferson regarding a specific proposed Bill in his day. However, there is a statement that prevents the Congress (the "State") from making laws establishing or prohibiting (a "separation") religion (which includes the "Church"). There's the lie. It means that the government has not right to force someone to worship; it does not endorse any form of worship; and it does not prevent anyone from worship.
Of course, there is some leeway inheritant to this separation. It is wrong for a public school to endorse prayer on its premises because prayer is a form of worship. However, where some have taken this to far is that they feel the school has to prevent worship in order not to endorse it. This idea is also a lie. It is a lie that fuels Churches in their lie. "See, they don't allow us to worship in schools!" Both positions are extreme. The interested parties on both extremes of this issue feed off of each other.
There is no wall. But there is designated limits on the authority of our government to impose its will upon the people. This is one of several cornerstones built into the Constitutional Amendments that prevents the majority of our population from oppressing any minority.
It also serves as a rule against the supporting of religion by public deeds or use of public funds. Again, some have taken this too far. Some have interpreted this prohibition of support to mean prohibition of religious activities on public school premises. They don't understand the difference between endorsement and equal access to public properties. As long as a Church pays the same as any other similar group renting a school auditorium, there is be no prohibition against that Church from renting it. If the school gave some sort of special "Church discount", then that would be an endorsement. The discount itself would be unconstitional, not the Church using the school facilities. This applied misunderstanding is more fuel for Churches to preach about how our system is being used to oppress religion. It gives them the opportunity to propagandize their lie about the First Amendment.