One of the most important dates in US history is the landing of the Mayflower pilgrims on the coast of New England in 1620. These pilgrims were Puritans who sought separation from the Church of England, seen as corrupt and oppressive. The Americans colonies were a haven for the persecuted, and those persecuted for religious reasons found there a land where their communities could flower and bloom in tranquility. Religious plurality is therefore a characteristic of early America. It is important because we have here an aspect that will later find its way into the Constitution.
In the 18th century, the Enlightenments reached their climax in Europe. By that time, Christendom had relinquished much of its religious fervor, and substituted for it a rationalist fervor. Yet, we would be mistaken in seeing even in this period a complete abandonment of any religious belief. Rather, this was a gradual process, that began not even with the Renaissance, but that progressively, slowly took shape. In the Renaissance, the principal topic for painters were taken from the Scriptures. Copernicus was also a priest and Newton had an interest perhaps as great, if not greater, in theology than in science. Darwin certainly had no intention of destroying Christianity to replace it with scientific reason. What all these exmaples show, is that while religion in general, and Christianity in particular, were not necessarily the target–this came later, and once again progressively–the interest was no longer on God but rather on the natural world.
Deism sought to answer this new situation, by leaving God as the ultimate cause of all, by now removed from human affairs. Thus, men were left with their reason to organize themselves into society, and to utilize nature to further their ends and improve their lives. In France, deism took a radical form, in the writings of Voltaire especially, in which everything that did not conform to reason was literally dangerous. This led to the infamous Terror, and the ‘cult of Reason’ installed during that time. France today is widely known as the model of a radical secularism, where even the slightest mention of the word God in public speeches is now unimaginable. In England, however, the situation was slightly different, in that the rationalist philosophy never reached such extreme. There never was a Terror there, nor were churches reconverted into ‘temples of Reason.’ This is the rationalism that the Americans inherited: the emphasis on the natural order, but a natural order that was not necessarily anti-religious.