At The American Scene Pascal-Emmanuel Gobry states:
To have a religion is to hold a belief about metaphysics. Either you believe that Allah is God and Muhammad is his Prophet or you don’t. If you do, and you eat pork, this will not make Muhammad more, or less, the Prophet. The two things aren’t related.
There are two issues which I think require some fleshing out. On the specific point about religion being about metaphysics, this is an intellectually respectable position, but I don’t think this describes at all the phenomenon of religion as it manifests in the minds and behaviors of most human beings. As an atheist I’m not too interested in whether God exists or not, I’m simply interested in constructing a model which allows me to describe and predict the behavior of religious people. A fixation on metaphysics, or matters of high philosophy, mislead more than not. From the perspective of atheists I think this presupposition confuses many of us into thinking that we can convince theists of the correctness of our position through argumentation and reason. I don’t think we can (and a theist may have the same problem with an atheist).
A more general issue is that I think it is not informative to reduce religion to some particular aspect or dynamic. For example, religion as belief, religion as practice, religion an expression of social will. Religion can be all of these things. Some of these things may be contradictory with others, but that matters little, as the human mind is a contradictory and slapdash construction.
Religious people who accept the belief propositions of their faith are going to differ with me deeply on the substance here. That’s fine. My main contention is that atheists who have little personal familiarity with the nature of religious faith too often lose sight of what religious people do, as opposed to what religious people say. They can be quite sincere in the latter, but far more relevant to us is the former. Accept not what they say, see what they do!