Upon my arrival in the United States the religious aspect of the country was the first thing that struck my attention; and the longer I stayed there, the more I perceived the great political consequences resulting from this new state of things.
In France I had almost always seen the spirit of religion and the spirit of freedom marching in opposite directions. But in America I found they were intimately united and that they reigned in common over the same country.
Religion in America...must be regarded as the foremost of the political institutions of that country; for if it does not impart a taste for freedom, it facilitates the use of it. Indeed, it is in this same point of view that the inhabitants of the United States themselves look upon religious belief.
I do not know whether all Americans have a sincere faith in their religion -- for who can search the human heart? But I am certain that they hold it to be indispensable to the maintenance of republican institutions. This opinion is not peculiar to a class of citizens or a party, but it belongs to the whole nation and to every rank of society.
In the United States, the sovereign authority is religious...there is no country in the world where the Christian religion retains a greater influence over the souls of men than in America, and there can be no greater proof of its utility and of its conformity to human nature than that its influence is powerfully felt over the most enlightened and free nation of the earth.
In the United States, the influence of religion is not confined to the manners, but it extends to the intelligence of the people...
Christianity, therefore, reigns without obstacle, by universal consent...
I sought for the key to the greatness and genius of America in her harbors...; in her fertile fields and boundless forests; in her rich mines and vast world commerce; in her public school system and institutions of learning. I sought for it in her democratic Congress and in her matchless Constitution.
Not until I went into the churches of America and heard her pulpits flame with righteousness did I understand the secret of her genius and power.
America is great because America is good, and if America ever ceases to be good, America will cease to be great.
The safeguard of morality is religion, and morality is the best security of law as well as the surest pledge of freedom.
The Americans combine the notions of Christianity and of liberty so intimately in their minds, that it is impossible to make them conceive the one without the other
Christianity is the companion of liberty in all its conflicts -- the cradle of its infancy, and the divine source of its claims...

From the book, "Democracy in America" by Alexis de Tocqueville