What Does Separation of Church and State Mean?

"While our Country remains untainted with the Principles and manners, which are now producing desolation in so many Parts of the World: while she continues Sincere and incapable of insidious and impious Policy: We shall have the Strongest Reason to rejoice in the local destination assigned Us by Providence. But should the People of America, once become capable of that deep simulation towards one another and towards foreign nations, which assumes the Language of Justice and moderation while it is practicing Iniquity and Extravagance; and displays in the most captivating manner the charming Pictures of Candour frankness & sincerity while it is rioting in rapine and Insolence: this Country will be the most miserable Habitation in the World. Because We have no Government armed with Power capable of contending with human Passions unbridled by  morality and Religion. Avarice, Ambition, Revenge or Galantry, would break the strongest Cords of our Constitution as a Whale goes through a Net. Our Constitution was made only for a moral and religious People. It is wholly inadequate to the government of any other" ~ John Adams