"We are," said Supreme Court Justice William O. Douglas, "a religious people," and his observation is continually borne out in every aspect of American public life. Religious ideals underlay the founding of the colonies and the firming of the new nation; the activities of churches have been closely interwined with politics in the abolition of slavery, the drive for women's suffrage, the prohibition of liquor, and the civil rights movement of the 1960s...