21 Little children, guard yourselves from idols. 1 John 5:21 (NASB)
Our English word idol is derived from the Greek εἴδωλον (eidōlon). Homer used eidōlon for phantoms and apparitions. In later Classical Greek, it carried the other non-religious meanings of picture, copy, or “any unsubstantial form, an image reflected in a mirror or water, an image or idea in the mind.”
In the Septuagint, however, eidōlon is used to translate some fifteen Hebrew words and always refers to the images of heathen gods and the gods themselves….
God’s second commandment in the Law, for example, prohibited making any “graven image” (Exodus 20:4; cf. Deuteronomy 5:8). Among many recurrences of idolatry, Ezekiel prophesied God’s judgment upon Israel for that abomination: “Your altars shall be desolate, and your images shall be broken: and I will cast down your slain men before your idols. And I will lay the dead carcasses of the children of Israel before their idols; and I will scatter your bones round about your altars” (6:4-5).