1. Who is G-d?
G-d is G-d. G-d is beyond and at the same time totally unified in a perfect continuous unity with His creation. G-d is the Creator. G-d created both the spiritual and the physical worlds. Do not confuse spirituality with G-d. All spirituality is a creation of G-d; His essential essence is beyond what we refer to as spirituality. When we speak of the G-d of Israel, we are referring to the G-d who revealed Himself to Avraham, Isaac and Jacob, and to the World at Mount Sinai. When we refer to G-d, we are referring to the G-d who made Himself known in an unprecedented event at Sinai, when He revealed His Will manifested in the Torah.
When we say G-d is One, we mean that G-d is One, not two, not three, not a thousand. We mean an absolute unity, without division, without form. Spirituality is related to physicality as a single, dependent, unified whole, as two sides of the same coin. G-d encompasses both sides, all sides, without any separation whatsoever. G-d being One, and the sole source of all existence, demands His honor not be shared. Only He must be worshipped and acknowledged as the single force enlivening and affecting the world. No opposites or forces exist outside of His unity. No power can act independently against His will.
2. What is Idolatry?
Idolatry is the acknowledgment of any power other than the One True G-d. Idolatry is the mistaken belief that any created entity is worthy of independent worship. Idolatry can take the form of attaching oneself to money, or material possessions, or attributing an inappropriate assessment to one's own worth or abilities, resulting in elevating oneself beyond universal human moral responsibility. On a deeper level, idolatry is attributing undue influence and power to the constellations, or attaching oneself in any manner of worship to a plant, an animal, angels or to a man. Any worship of creation, as opposed to the One Sole Creator, is idolatry. This is true even if a person knows that G-d is the Supreme Being and worships creation in conjunction with G-d as an act of "glorifying G-d". As written by the Prophet Isaiah in the Name of Hashem, "I Am Hashem, that is My Name; I will not yield My glory to another, nor My renown to idols." (Isaiah 42:8)