Not really, because what you base it on is a very narrow conception of how people regard the spirit world from interacting with the real world, and how "secular" power is considered as proofs of "sparks of divinity" in those individuals fortunate to have it.
For example, the hero cults in Hellenistic Greece and the imperial cults in Rome are highly interesting in these respects.
The historian Price has written an excellent, and still considered seminal, study on the Roman Imperial Cult in Asia minor, "Rituals and Power: The Roman Imperial Cult in Asia Minor "
This book has university academic standard, and was used in my stint at studying history at oslo University.
Here's the Amazon link:
https://www.amazon.com/dp/052131268X/?tag=pfamazon01-20
My main point of contention though, are what WORDS are appropriate in history, and which we should not use.
The couple "essential/inessential" is basically either rhetorically pointing at som "eternal essence" (and I do NOT think you intended that), OR, as a quantifying measure of relative weights.
But, quantification of the importance of different causes in history is highly suspect, or must be used with extreme caution, and we need a more modest idea besides:
To which extent our sources seem to indicate that analytically separate ideas were intertwined in some particular culture, or equivalently, how "separate" those ideas where.
(Judeo-)Christianity is quite unique in this degree of separatedness of the sacred and the secular, the normal picture seems to indicate a much stronger degree of intertwining.
BTW, Price* is quite adept in showing that in terms of quantification, LOCAL status competition for construction of imperial cults was probably more important than heavy-handed, centrally directed adoration policy from the Roman State.
It was the LOCAL magnates, in scurrying not just for (or even mainly for) imperial favour, but in order to be resplendent in the eyes of the local population by having a "closer tie" with the almost-divine, far-off Emperor through his temple construction in his honour..
More than enough sources indicate that the Emperors themselves were rather embarassed on the personal level at the prevalence of this religio-political "Greek" phenomenon, closely related to the city-state structure of Asia Minor.
*Whose main laudable effort in that work is to "de-Christianize" religion as such, in particular opposing the traditional view that worship of a living, or dead, person, was some sort of "debasement" of religion for "mere political" reasons. Rather, the mentality landscape, Price argues, between religious might and secular power should NOT be regarded in such a way that the clear distinction between "religion" and "politics" is to be assumed to have been felt as "natural" as it is for cultural Christians.