John Adams on Religion and the Constitution
Found in: The Works of John Adams, 10 vols.
This quote is from John Adams (1734-1826), a signatory of the Declaration of Independence, one of the framers of the Constitution, and the second president of the United States of America. This quote, and especially its famous last line, expresses a sentiment widely held among the statesmen of the Founding Generation that no matter how well a constitution is constructed, It will not insure freedom and prosperity unless it is supported by a moral, virtuous population.
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 practising iniquity and extravagance, and displays  in the most captivating manner the charming pictures of candor, frankness, and 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 gallantry, 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. (FROM TO THE OFFICERS OF THE FIRST BRIGADE OF THE THIRD DIVISION OF THE MILITIA OF MASSACHUSETTS, 11 October, 1798)