Separation of Church and State is a founding principle regardless of how many times religious right assholes insist of denying or lying about it. One of the more recent dumb-fucks to try ranting about it can be found on Patheos. Bethany Blankley's "'Separation of Church and State' Is Not in The U.S.Constitution" does not seem to be simply a matter of ignorance. There are some hints that she does actually know that what she is saying is neither accurate or honest.
It is not just that she focuses on the exact phrase "separation of church and state" since a lot of religious conservatives have used the same bogus argument. She is very careful about how she talks about the "Founding Fathers". For instance in the second paragraph she states:
"In fact, not one of the ninety Founding Fathers stated, argued for or against, or even referred to such a phrase when they debated for months about the specific words to use when writing the First Amendment. Congressional Records from June 7 to September 25, 1789 reveal that none of these men, including Thomas Jefferson, ever used the phrase, 'separation of church and state.'"
I have not checked to verify the statement in part because it does not actually matter. It is irrelevant to her argument for two main reasons. The first being that if it matters what the founders really believed she would not limit their thoughts and writings to a single date set. Many of the founders did comment on separation at various times before and after the Constitution was written. In "fact" the phrase's origin can be traced to Thomas Jefferson. The other glaring problem with this and the premise of the entire piece is that the exact phrase is not what is at issue. The concept is expressed clearly in the 1st Amendment regardless of the precise phrasing.
It is both irksome and entertaining that people like Blankley constantly use the same feeble and intellectually bankrupt ploys over and over again. What this unethical bitch seems to conveniently overlook is that her low standards are far worse in their consequences for her own goals. By her own argument I can clearly state that not only is the Constitution secular but that it goes even further. It must be anti-religious if exact phrasing is the standard that matters most. The words "God", "Jesus", and "Christianity" do not appear anywhere within the text. The two references that can be said to be religious are framed in the negative. So, by Blankley's logic the Constitution can only be against religion.
Fortunately for slimy weasels like Blankley that is not how our government actually works. The Constitution was designed to protect the rights, religious or otherwise, of all.