Back at the University of Essex in the 1980s religion simply wasn't an issue for us. I suspect that there were a few (more?) quietly religious people attracted more to Heidegger, Derrida and writers talking about the Other with a capital "O", but they never made their faith, or faith as such, into an issue. It just never came up for discussion, as far as I can remember.
In truth, religion persists. Take a short walk from the academy in any direction and you will soon meet people for whom there is more than can be grasped by the modern mix of science, epistemology and the dubious ethics within the limits of modern rationality (Kant, Rawls, Habermas, et al).
The question is: is this a sign that the Enlightenment didn't drive its message home hard enough and really sweep away the last vestiges of medieval mysticism or is the persistence of religion a sign that the Enlightenment was lacking? I used to believe the former but slowly I have come to feel that the latter is where the truth lies.
One issue is death. For the Enlightenment death is passed over in silence or left as a fact among other facts (perhaps being lumped in with an understanding of how organic matter is composted). Is it necessary to argue that this is a failing, that it is just plain unacceptable when seen from the standpoint of someone whose loved one has died?
The shortcoming is evident in Marxism. Does Marx anywhere concern himself with the death of the worker? How will the worker die? What will his/her death mean? How important is it that the culture (any culture worth affirming) embrace death and give it significance instead of ignoring it or treating it as just another moment in a cycle that is adequately described by organic chemistry?