The first chapter of Romans contains a particularly harsh denunciation of what appears to be OT type idolatry, the worship of graven images. Certainly my standard picture of idol worship has almost always been that of some pagan bowing down to a piece of rock carved to resemble some animal or supernatural creature of some sort. I suspect that is what comes to mind for most when they hear the term idolatry.
That particular notion of idol worship may be in the background of what Paul is saying in Romans here, but I suspect that he is more concerned with a type of idolatry which now permeates most of Orthodox Christianity, the veneration and outright worship of the Bible, the institutional church, and the church's liturgy, doctrines, and leadership. It is reasonable to conclude that whatever I have faith in as my conduit or connection with God is as much divine as God, Himself. All objects in which I have faith as essential to my spiritual well-being are co-equal with God, the Creator, in terms of establishing my eternal welfare.
Men in all ages have sought physical, tangible elements as an outward symbol or expression of their religious beliefs. This seems totally natural to the human mind. Religion addresses a realm or reality which is not visible and accessible in the physical sense, while as humans we are totally attached to the physical realm. Nothing could be more comforting than clinging to physical objects or symbols as an expression of religious thought and belief.
That being said, it becomes easy for our minds to substitute these symbols for actual faith in God. When one insists that God's revelation is confined to the words on a page, that God' blessing is restricted to those in the church, and that only God called ministers can rightly instruct in righteousness, that implies that God cannot speak for Himself, cannot exercise His own Will in blessing mankind, and cannot instruct personally in abundant living. Anything or anybody which is allowed to intervene between me and God is an impediment, a limitation, a force greater than God. It is an idol by any practical definition of the term. As I suggested before, in that respect, Orthodox Christianity is full of idols.
One of the specific items, which Paul denounces in Romans 1, is the practice of casting God in the image of man. This is particularly significant, because much of Christian doctrine does exactly that. In defining God as vengeful, arbitrary, jealous, and self obsessed, Christianity's interpretation of God most definitely mirrors the human family's least admirable qualities. No matter how they try to gloss over this evident fact, what the church has created is a god who is the exact mage of corruptible man, the very thing Paul condemns. Simply saying that this is the Bible picture of God and it therefore must be accepted is no real explanation of anything. It is a simple evasion, a failure or refusal to deal with the fact that Orthodoxy's god is not admirable, noble, or majestic in conduct, thought, or attitude.
Most certainly, there is a disconnect somewhere. God cannot operate as Orthodoxy describes Him and remain a transcendent, transformative force in the universe. A god cast in the image of man, as the god of Orthodoxy most certainly is, is a part of a system which rivals OT idol worship in terms of misdirecting mankind away from a right understanding of their Creator.