Many of the commandments that apply to gentiles do not easily lend themselves to classification into any one of the Seven Noahide Laws, treated here as seven categories for other commandments and rules. To decide under which heading a given commandment belongs, we must first define the category according to its essence.
Strictly speaking, idolatry is believing in the power of any entity besides the one G-d, or any act of worshiping such an entity. But many commandments may seem relevant to both idolatry and blasphemy, a related concept. What differentiates idolatry from blasphemy? Lichtenstein, in his book The Seven Laws of Noah, tries to define them thus:
the Idolatry area regulates mans theistic affairs in his relationship with the mundane, and
the Blasphemy area regulates mans theistic affairs in his relationship with the Divine (p. 78). This scheme tries to classify commandments from the vantage point of man in the physical world, groping in the darkness and searching for G-d; it starts with the material and looks for the spiritual. It is a definition of superficial, external characteristics, and thus leaves many gray, undefined areas between idolatry and blasphemy.
Hasidus (the inner meaning of Torah), on the other hand, starts from G-ds perspective and looks downward into the creation, defining things according to their essence.
From this vantage point, one can better define idolatry, and its close relative heresy, as: the refusal to acknowledge Truth and its sources.
Who is the idolater? He is one who credits a false deity for his success or failure; he believes a false religion, listens to false prophets and teachers, and reveres and studies false scriptures. He does not recognize the Truth or its sources. One who rejects idolatry, on the other hand, is one who believes in and worships only the true G-d, listens only to true prophets and teachers, and studies the authentic Torah only according to its true meaning.
Idolatry, then, is best defined as the rejection of Truth as such, whereas blasphemy involves ignoring or opposing the permeation of holiness into the physical world. Consequently, we classify here all commandments related to the acknowledgement of G-ds Truth and its authentic sources.