That depends on how we define essence. But it surely will always be a generalization. No doubt about that. But such is the nature of social phenomenas. You can never fully comprehend them, so you generalize to get at least as close as possible.
As said, in this context I understand essence as what defines a specific social institution. And by defines I mean what is its fundamental difference to other social institutions.
If you accept that identifying the category of "religion" necessarily involves generalisation, then why do you also suggest that we should look for some essence? Why not just adopt a fully contextual understanding of religion, as something ultimately inextricable from its human context? I'm not trying to pull some sort of "a-
ha!" move, I honestly don't understand why you're accepting what appear to be two distinct premises.
In case of religion, it is that its foundation is of a metaphysical nature by definition. You can't have religion without that. Then it is an ideology or whatever.
As Park says, this is pretty problematic. Confucianism becomes a mere set of traditions, while Platonism becomes as much a religion as Islam. So it doesn't really work either as a category that includes much of what is generally understood as "religion", or that excludes things which generally aren't.
And then one may ask what does this metaphysical nature offer others can't - so again what defines it? I would say that there are no direct constraints by the observable world to its message.
And to what purpose is that used? Naturally, to serve the emotional needs of people. But again we may ask, in what way can those metaphysics serve emotional needs other things can not? I would answer that with an absolute and universal source of meaning (and hence in a certain way security, orientation), not constrained by the limitations of the observable world.
And that's where I arrive at the conclusion:
The essence of religion is the emotional need of people for an absolute sense of meaning.
I personally don't care how that is achieved. But it is my impression that every religion does that. Of course, I can be wrong and would be very interested if you knew a religion which doesn't.
What is "meaning", in this sense? Are you suggesting something narrowly teleological, which plenty of religions
do reject, or simply in a looser sense of identifying a "place" for humans in the universe, which could be said of plenty of non-religious philosophies? Some of animistic belief-systems identify no fundamentally different place for humans in the universe, simply identifying them as one form of life among many (albeit invariably distinguished in various not-insignificant respects)- does that constitute offering "meaning"? Or how about Marxism, in which humans are located within a process of historical development, and offered some direction for further development- is that "meaning", and so is Marxism a religion? (Marx certainly had a metaphysics, albeit an insufficiently developed one, and various successors offer more complete models.) So this is a claim that really needs to be expanded upon.
Besides, this is getting away from Whiksey Lord's original claim, which more narrowly suggested that religion could be understood in terms of a "caring universe" and what he above calls the "immortality fantasy". Which is even narrower set of claims with even more specific presuppositions, so demanding even more expansion.
