The doctrine of “Separation of Church and State” is not even a doctrine. It is simply a line out of one of Jefferson’s letters. To consider it a constitutional mandate would be like taking a sentence from Washington’s letters and calling it a mandate.
This “mandate” is endlessly pushed because it gives liberals and Democrats a method to push Christianity out of public life. Eventually they will push it out of private life too, since private thoughts are often led by public opinion. That is the reason that a quotation from Jefferson, who wasn’t even at the constitutional convention, is treated like part of the constitution. There have always been many anti-Christian elites in America, be they in government, academia, or business: the quote from Jefferson is just a handy tool for their campaign.
The constitution states that “Congress shall make no law respecting an establishment of religion,” which means that Congress can’t create a national church, like England has. The constitution, contrary to liberal dogma, does not have the least word to say about states establishing state religions, and in fact they have the right to do so. This isn’t to say that they should. States also have every right to encourage Christianity, or to leave it utterly to private efforts. The liberal judges that have assailed Christianity for the past century from the bench haven’t had, in most cases, a leg to stand on. Many state laws have been shot down because the constitution supposedly prohibits states to have anything to do with religion. But that is false, as shown above.
 Jefferson was in France at the time, serving as our ambassador.