1. Is accepting upon myself the authority of the Knesset to legislate laws idolatry in essence?
2. How is this different from the authority of the Talmud, which arose from below through acceptance by the Jewish people and not from an argument that this is what God wanted?
3. Why do you need an object for the formal definition? Just as God is not a tangible object, so too apparently there should be room in the definition for idolatry. (If you mean a non-tangible entity, then I do not really understand what takes that out of the definition.)
4. As a continuation of question 3: if in essence idolatry has not disappeared from the world but has only changed form, then all the Jewish laws connected to idolatry would have to undergo adaptation and remain relevant in our time as well (a conservative midrashic move), no?

1. I addressed that there too. In my opinion, no—unless you give it authority by virtue of its being the Knesset itself and not because of some reason. Any rationalization you have for granting that authority takes it out of the category of idolatry.
2. The assumption is that God wants us to follow the decision of the public. In the end, it is His own will. It does not necessarily fit His specific will (regarding the rival wife of one's daughter, or a particular halakhic topic), but He has a will that we act this way, just as we heed the ruling of the sages (in Torah-level law) even though it is not necessarily His will. This is the "My children have defeated Me" of the Oven of Akhnai.
3. A non-tangible object. Enoch, for example, argues that morality is binding even though there is no object behind it at all, neither tangible nor non-tangible. Because if there is an object behind it, then by definition that is God. (That is how I define God—the object that gives morality its validity.) Every atheist who is committed to morality holds such a position.
4. Why do you think anything has changed? Back then, could they not also grant authority to an abstract object or to no object at all? I am not sure. But in principle, if that is the case, you are right.

1. Even if I have a rationale for why I obey the Knesset as a source of normative authority, I would ask about the rationale itself: why is it not idolatry? (Unless the bottom-most turtle is God.) Is most of humanity idolatrous in accepting political authority, or perhaps they are hidden believers?
2. From where do we get that assumption? This too is a question we have discussed in the past, and there is no need to elaborate if you simply “see” that it is the divine will to follow what our ancestors accepted as a source of authority.
3. I am pretty sure Enoch is a realist who thinks there are moral entities. I am not entirely sure what the substantive disagreement between you is after watching the debate and your discussion on the site afterward. In any case, I cannot understand why someone committed to a normative system with no object behind it would not fall under the formal definition of an idolater—but formalism is not my strong suit.

1. The rationale begins with some value. That brings us back to the question of the basis of values. In my opinion, that can only be God. Obedience to the state as an independent basis is fascism. That is not common in our circles.
2. Indeed, from reason. One could say that this is even a moral value: to act in accordance with the decision of the group you belong to (unless there are strong counterconsiderations).
3. Indeed. Precisely on that point I also do not understand him. He talks about realism and evades the ontic question.

As for the prohibition of idolatry, on the straightforward level there is a difference between not being obligated to the Holy One, blessed be He, and being obligated to someone else—which is idolatry. When there is no object behind the norms, it is hard to say that you are obligated to someone else. You are obligated to floating norms, and this is an obligation to behavior, not to another god.