Idolators are not Stupid

 Derashos HaRan (04): For there is no question that those who were drawn after idol worship and who became its devotees, as we learn from Scripture and from the words of our sages— there is no question that they were not fools. Beyond a doubt, experience confirmed them in their expectation of benefit from their idolatrous acts, for if this were not the case, so many sound individuals would not have strayed into idolatry generation after generation. But it is as we have said. In the early times there were many acts which were known to result in great benefit. There was no error on this score but only in the conception of the means by which this benefit was derived. In reality, it derived solely from the nature of the thing acted upon; but the practitioners of these acts attributed the benefit to the will of the acting and protecting agency and compounded their sin by bringing offerings and sacrifices to the heavenly host. It follows from this that anything which is known to derive from the predisposition of the recipient is beneficial in truth and permitted by the Torah, and what is thought to derive from the will of the celestial agent is vain and empty and in the realm of idolatry. Therefore, every act which does not contain the intent of drawing-down the favor of a celestial agent and which is not distinctly idolatrous is not in the forbidden category of "the ways of the Emorites."