I think you and I are on essentially the same wavelength Eikadistes. Epicurus is saying that there is a mechanism going on in the human brain which senses or conceptualizes or recognizes a partter as "divinity." It's as improper to reject the existence of that mechanism as it would be to reject the feelings of pleasure or pain or sight and sound. Epicurus participated in ceremonies (at least in some way) and had a view of a "true piety." But seemingly never once endorsed a specific statement about the actions of an individual god, and the fact that he may have made general references in an allegorical way (as did Lucretius) to a Zeus or a Venus don't conflict with that.
As to whether they were talking past each other in the ancient world I am not sure. However I think we can say that's happening today. It's one thing to specifically reject Allah or Jehovah or some other specific assertion about a particular god. I feel sure that Epicurus would agree with rejecting all those assertions. But "modern atheism" seems to be stuck in the same pattern of dismissing all talk of any kind of "gods" whatsoever as improper. Maybe worse, modern atheists also seem to consider all talk of divinity to be essentially a disease or a sickness. That is the equivalent of seeing pleasure or pain as a disease or a sickness instead of being inherent parts of our nature as human beings to be understood and developed properly.
So I'd say as an analogy that Epicurus would say that it's as insane to reject all discussion of divinity as it would be to reject all discussion of pleasure and pain.
This is an area where Epicurus has a lot to teach many people with whom most of us here agree on many things. In many cases the the modern diagnosis of the problems caused by religion are less advanced than was the diagnosis of Epicurus 2000 years ago.
It's not a matter of protecting oneself from religious zealots by playing along with their fantasies. The more important issue is to work with human nature, rather than against it.
