Second, American religious communities were often strong supporters of disestablishment. Dissenting Protestants had a long history of resentment for the established English church. Others -- Catholics and Quakers -- were minorities suspicious of majority religious rule. Christians generally saw state intrusion as a threat to their theological integrity, and worldly power as a diversion from their mission. They supported disestablishment for the sake of the church. And their political independence contributed to their religious vitality.
Third, as my co-author Pete Wehner and I argue in "City of Man: Religion and Politics in a New Era," America was not founded as a Christian nation precisely because America's founders were informed by a Jewish and Christian understanding of human nature. Since humans are autonomous moral beings created in God's image, freedom of conscience is essential to their dignity. At least where the federal government was concerned, the founders asserted that citizens should be subject to God and their conscience, not to the state.
The Founders were not secularists. They assumed that people would bring their deepest moral motivations to political life -- motivations often informed by religious belief. But they firmly rejected sectarianism. America was designed to be a nation were all faiths are welcomed, not where one faith is favored. This was and is the American genius.
So does the Constitution, in Jefferson's gloss, require the "separation of church and state"? Institutionally, yes. Theologically, yes with one notable exception. Nearly all the most important teachings of faith -- doctrines on individual salvation or the destination of history -- have no public role or relevance. They are compromised by contact with power. But one belief -- a belief in the nature and rights of human beings -- is the basis of any political philosophy, including our own. It matters greatly if "all men are created equal" or not.
Religious faith remains one of the main foundations for belief in human equality and dignity -- as it was in the Declaration of Independence. But this conviction leads in a different direction than some religious people imagine. It is honored by respecting the priority of conscience.