In the European enlightenment, there was an underlying presumption that science ought to replace 'religion' as the source of normative judgement. However science is not directly concerned with ethical questions - it is mainly concerned with measurement, prediction and exploration of the natural world. The scientific attitude has been generally associated with the tendency towards positivism in philosophy, which is the rejection of metaphysics and many other facets of traditional philosophy.
‘Positivism’ was a term devised to differentiate the empirical and natural sciences - 'positive sciences' - from prevailing religious and metaphysical philosophies of the age. Auguste Comte, who coined the word, saw a progression in the development of society from the ‘theological’ to the ‘scientific’ phase, in which data derived from empirical experience, and logical and mathematical treatments of such data, provide the exclusive source of all authentic knowledge. The general conception of the evolution of society from theological to scientific - a model which might be called ‘historical positivism’ - has remained an important component of the modern outlook. In this world-view, the mechanistic model and the idea that the underlying reality of the Universe was matter was, then, the culmination of the idea of Progress. In important respects, science assumes the role that was previously occupied by religion, to become something like a 'religion of scientism' which has recognizable exponents in modern society.
Secular thinking, conceived as a systematic philosophy which does not make recourse to anything metaphysical, accepts the natural sciences as the umpire of reality, understanding of which is always to be sought in objective terms. Within this view, individuals are free to practice within any religious or spiritual tradition of their liking, with the proviso that it ought not to be harmful to others. But note that this radically subjectivizes the question of the validity of the truth claims of any such traditions. In practice, it is impossible to differentiate such truth claims from matters of opinion, because they are basically subject to individual conscience and beyond the purview of the objective sciences.
What I think is lacking in all of this is a model which accomodates the fact of spiritual enlightenment. There was really no idea of such a thing in the ecclesiastical traditions that the Enlightenment reacted against, where 'spiritual enlightenment' in the Eastern sense was generally the subject of ecclesiastical censure and persecution. If such an understanding is to be found, I think it has to be sought through comparitive religion, anthropology, and the study of what William James called 'the varieties of religious experience'. And I think if you do study it that way, with an open mind (which is a very hard thing to come by in regards to this question) you can see the outlines of what 'spiritual awakening' across many different cultural traditions really consists of.
One of the groundbreaking popularisers of comparitive religion, Huston Smith, addressed this in his book Forgotten Truths in which he says that in all the sacred traditions, there are "levels of being" such that the more real is also the more valuable; these levels appear in both the "external" and the "internal" worlds, "higher" levels of reality without corresponding to "deeper" levels of reality within. On the lowest level is the material/physical world, which depends for its existence on the higher levels. On the very highest/deepest level is the Infinite or Absolute, which might be identified as God in the theistic traditions. (The key point, the single most important understanding that was lost in the European Enlightenment, was the notion of a 'hierarchy of being'.)
Basically his Forgotten Truths is an attempt to recover this view of reality from materialism, scientism, and "postmodernism." It does not attempt to adjudicate among religions (or philosophies), it does not spell out any of the important differences between world faiths, and it is not intended to substitute a "new" religion for the specific faiths which already exist.
Nor should any such project be expected from a work that expressly focuses on what religions have in common. Far from showing that all religions are somehow "the same," Smith in fact shows that religions have a "common" core only at a sufficiently general level. What he shows, therefore, is not that there is really just one religion, but that the various religions of the world are actually agreeing and disagreeing about something real, something about which there is an objective matter of fact, on the fundamentals of which most religions tend to concur while differing in numerous points of detail (including practice).
I would hope that some kind of common vision is beginning to emerge from the Western encounter with Buddhism as well as from other sources. If we are able to construct a cosmology within which the fact of spiritual awakening retains the pivotal importance that it has always had for Buddhism, there is no reason why this can't accomodate, and also counter-balance, anything which the objective sciences discover. In its absence, however, we are facing only ever-increasing and more sophisticated forms of avidya which is a threat to both the human and natural environment.
(Originally posted on Dharmawheel).