What enables religion to spread?
Question: why religion spreads among (some) human beings? What is it about them that enables the transmission of religion?
This issue allows multiple answers. In this post, I would like to focus on the simplest answer to the question. In my theory, I presuppose an answer to the question: I assume that there is something in our constitution that allows religion to spread among human beings. The issue now is: why do I presuppose it, i.e. assume this state of affairs as a fact?
The reason is also simple: I do not know how to go about answering this question or even where I have to look for an answer. Let me explain. Should a theory of cultural difference answer this question? Should a theory of religion answer this question? Should evolutionary psychology answer this question? Should individual psychology answer this question? Should evolutionary biology answer this question?
If a theory of cultural difference should answer this question, then that is because one can show that the cultural psychological difference between two cultures allow for the expansion of religion In that case, probably the answer will be partial: from where does the difference in cultural psychology emerge?
Should a theory of religion answer the question? In that case, it is in the nature of religion to create the conditions of the transmission of religion. If a theory in evolutionary psychology answer this question, then that is because it identifies some inherited evolutionary aspects of our psychologies (in all cultures) that allow in some cultures the propagation of religion. (In such a case there is some or another psychological need that can be filled by religion in one case and something else in another case.) If individual psychology were to answer this question, it does so by identifying the characteristic patterns (let us say) of a person that allows for his conversion. If evolutionary biology can answer this question, then it will either be in the direction of cultural psychology, or identify the adaptive property of religion or falsify my hypothesis.
In other words, it is unclear which theory should answer this question. At least the above theories are all candidates for answering this question (may be even sociology is one such candidate) Currently, because I have no idea how to answer this question I simply take it as a fact that religion exists among (some) human beings and try to understand its transmission by formulating hypothesis about its dynamic.
One of the very typical uncertainties in the course of emergence of a scientific theory is the above kind of ambiguity. For instance, in the early days of theory of electricity, it was unclear whether the twitching of legs of a dead frog when electrical current passed through them should be explained by theories of electricity or through theories in biology. What kind of a phenomenon was this?
In the same way, your question, though completely reasonable, carries the same uncertainty. However, all I can say at the moment is that I have no idea where one should look for an answer: in individual psychology, in cultural psychology, in sociology, in evolutionary psychology, in evolutionary biology.