Many contemporary naturalists believe that with the critical work—the critique of the truth-claims of theism—essentially done by Hume, we should turn, setting both metaphysical speculation and fideistic angst aside, to naturalistic explanations of religious beliefs. The main players here from the nineteenth century are Ludwig Feuerbach, Friedrich Engels, Karl Marx, Max Stirner, and Friedrich Nietzsche; and from the twentieth century Emile Durkheim, Max Weber, Axel Hägerström, Sigmund Freud, Bronislaw Malinowski, and Antonio Gramsci. Their accounts, although varied, are all thoroughly naturalistic.
These naturalists assume that by now it has been well established that there are no sound reasons for religious beliefs: there is no reasonable possibility of establishing religious beliefs to be true; there is no such thing as religious knowledge or sound religious belief. But when there are no good reasons, and when that fact is, as well, tolerably plain to informed and impartial persons, not crippled by ideology or neurosis, and yet religious belief (a belief that is both widespread and tenacious) persists in our cultural life, then it is time to look for the causes—causes which are not also reasons—of religious belief, including the causes of its widespread psychological appeal for many people. And indeed, given the importance of religious beliefs in the lives of most human beings, it is of crucial importance to look for such causes. Here questions about the origin and functions of religion become central, along with questions about the logical or conceptual status of religious beliefs.
(Kai Nielsen, “Naturalistic Explanations of Theistic Belief,” chap. 51 in A Companion to Philosophy of Religion, ed. Philip L. Quinn and Charles Taliaferro [Malden, MA: Blackwell Publishers, 1997], 402-9, at 404-5 [italics in original])
Note from KBJ: Theism is the belief that there is a god. Atheism is the belief that there is no god. If one belief cries out for causal explanation, so does the other. Religion is a social institution. Irreligion is a social institution. If one institution can be understood in terms of its origins and functions, so can the other. Atheists assume that theism is false and try to explain its persistence. Their explanations make reference to such things as the need for a heavenly father. Theists assume that atheism is false and try to explain its persistence. Their explanations make reference to such things as rebellion against the heavenly father. That naturalists think their approach undercuts only theism, rather than both theism and atheism, or only religion, rather than both religion and irreligion, suggests that they’re not as intelligent as they think they are.