America is a product of the European Enlightenment. Of the thought of Diderot, Montesquieu, Voltaire who gave us the idea of human rights partially owing to the earlier thought of John Locke. Enlightenment is the breakthrough that defined the European civilization. It is founded on the assumptions that human reasoning can reach insights and results about how people should be governed. These insights do not come from sources of eternal wisdom - whether they be Christian, Judaic, Muslim or Taoist - or those of "native" peoples. They come from current rational debate that chooses its sources of knowledge on the basis of reason. Knowledge coming down to us as an authoritative teaching of wisdom is to be excluded from participation in the political process. This is especially true of teachings of religious nature. Knowledge influencing the political process and ideologies is to be secular in nature.
America is conflicted about the nature of its civilization - in a way it is an adolescent child of Europe. America has a strongly religious population that professes the Judeo-Christian religious tradition as a founding principle of its political system. I hope America will deal with its religious legacy without a major conflict and resolve it in a manner similar to Europe. Europe has already determined that as a civilization it will not allow religious teachings to determine political choices. Despite, or perhaps due to, much longer religious tradition and religious conflict, Europe has decided, more or less at the end of the 30-year war in 1648, that religion is a matter of private individual choice.
Both America and Europe are getting themselves into a lot of trouble by allowing the settling of large minority populations that profess adherence to varieties of religious beliefs and wish to be governed by principles derived from those beliefs. The adherents of Islam even make the claim that they will never stop to strive for the whole world, or a country or civilization, to be governed by a law flowing from the teaching of Islam. Islam is the religious movement most visibly incompatible with the idea of secular civilization, but other religious ideologies - such as Russian Orthodox or American fundamentalism - should also be viewed with suspicion.
Multiculturalism is the idea that various religious ideologies can be reconciled and find some compromise while being allowed to participate in the political process. In other words that the political power structure can be the result of a compromise between rivaling religious traditions. Multiculturalism has been to a large degree promoted and adopted as a project in the US and Europe - and leads us in a dangerous direction. It leads toward religious conflict and civil war because many religions espouse intransigent totalizing views of the origins of authority and law. A religion, in its essence, is a response to a basic human subjective anxiety of death, a response becoming an institution and an objective source of authority and power. The roots of religious feeling are immensely strong as they reach into this basic existential anxiety and therefore religion is especially dangerous when it is allowed to play a role in the political realm of power.
The achievement of secular civilization is to limit the reach of religion and bar it from entering the realm of temporal power brokering on the national or social scale - known as politics. The discourse over political ideology, of the law, of political figures, of economic choices, artistic expression, - is then allowed to be free. Free from the imposition of totalizing sources of authority which bind us into the basic anxieties of our life. That subjective problem is best dealt with privately or as a matter of private choice in the so-called communities of faith that are free to operate as enclaves within the secular civilization.
This is of course written in the wake of the terrorist attacks against "Charlie Hebdo" on January 7, 2015 (and now after the Copenhagen attacks on Feb 14-15) and after public reaction condemning violence with roots in Islamic religion. Secular civilization that has overwhelming support in Europe and America has of course its implementation problems, identified variously as racism and colonialism, and these can be addressed in the atmosphere of safe public debate, with free speech, free from religious terrorism and other irrational prejudice.
We need to support the secular civilization as it respects religious freedom among other freedoms. Religion needs to respect the secular civilization.