The category "secular" developed largely within Latin Christendom, initially as one term of a dyad contrasting profane time with the eternal, or sacred time. Certain places, persons, institutions, and actions were seen as closely related to sacred or higher time, and others as pertaining to profane time alone--thus the similar distinction made in the dichotomy of "spiritual/temporal" (for example, the state as the "temporal arm" of the church).
So one obvious meaning of "secularization" dates from the aftermath of the Reformation and refers specifically, in this sense, to the moment when certain functions, properties, and institutions were transferred from church to lay control. From the seventeenth century on, however, a new possibility arose--a conception of social life in which the secular was all that existed. Where "secular" had originally referred to profane or ordinary time, now profane time came to be understood on its own, with no reference to "higher" time. The meaning of "secular" was thus profoundly changed, because its counterpoint had been fundamentally altered. Gone was the contrast with another temporal dimension in which "spiritual" institutions had their niche; rather, the secular, in its new sense, opposed any claim made in the name of the transcendent. Needless to say, those who imagined a "secular" world in this sense saw claims regarding the transcendent as unfounded, and tolerable only to the extent that they did not challenge the interests of worldly powers and human well-being.
This shift brought a new conception of good social and political order, one unconnected to either the traditional ethics of the good life or the specifically Christian notion of perfection (sainthood). This new idea envisioned a society formed of and by individuals to meet their needs for security and the means to life. The criterion of a good society in this outlook--mutual benefit--was not only emphatically "this-worldly" but also unconcerned with "virtue" in the traditional sense.
The breaking away of a specifically "earthly" criterion was part of a broader distinction, one that divided "this world," or the immanent, from the transcendent. This clear-cut distinction has become part of our way of seeing things, our Weltan schauung, in the West. We tend to apply it universally, even though no such hard-and-fast distinction has existed in any other human culture. What does seem to exist universally is some distinction between higher beings (spirits) and realms, and the everyday world we see immediately around us. But these are not usually sorted out into two distinct domains, with the lower one seen as a system understandable purely in its own terms. Rather, the levels usually interpenetrate, and the lower cannot be understood without reference to the higher. Yet the new understanding of the secular that I have been describing builds on precisely such a separation. It affirms, in effect, that the "lower" order--the immanent or secular--is all there is, and that the higher, or transcendent, is merely a human invention.
At first, the independence ascribed to the immanent was limited and partial. In the Deist version of this claim, widespread in the eighteenth century, God was seen as the artificer of the immanent order. Since He is creator, the natural order stands as a proof of His existence; and since the proper human order of mutual benefit is one that He designs and recommends, we follow His will in building it. The Deist conception, furthermore, affirmed that He backs up His law with the rewards and punishments of the next life. Thus, some religion, or at least a certain piety, is a necessary condition of good order. Religious authority can enter into competition with secular rulers; it can demand things of the faithful that go beyond, or even against, the demands of good order; it can make irrational claims. So it remains important to purge society of "superstition," "fanaticism," and "enthusiasm. …