An Evangelical acquaintance--who emphasized that he is not aiming to be antagonistic--has asked me to explain how the use of icons does not constitute idolatry and violate the second commandment in Exodus 20:4-6. His interest has prompted me to investigate the issue further.
Often brought up to give Old Testament support for this controversial practice are the divinely-commanded placement of two cherubim on the mercy seat, the construction of the salutary bronze snake in the middle of the camp, and the decoration with images of Solomon's temple. These comparisons seem to fall far short of what is required, however; it seems highly unlikely to me that the Israelites were in fact venerating angels while prostrating before the special vessel of God's presence. Did the Hebrews ever believe in and practice something resembling what is found in Orthodox Christianity?
Further, the incident surrounding the golden calf--recounted in Exodus chapter 32, but without the degree of clarity that I was hoping for--seems to cast the use of icons in a profoundly negative light. The description of this sorry event is presented below, taken from the RSV, with my emphasis added.
 When the people saw that Moses delayed to come down from the mountain, the people gathered themselves together to Aaron, and said to him, "Up, make us gods, who shall go before us; as for this Moses, the man who brought us up out of the land of Egypt, we do not know what has become of him."
 And Aaron said to them, "Take off the rings of gold which are in the ears of your wives, your sons, and your daughters, and bring them to me."
 So all the people took off the rings of gold which were in their ears, and brought them to Aaron.
 And he received the gold at their hand, and fashioned it with a graving tool, and made a molten calf; and they said, "These are your gods, O Israel, who brought you up out of the land of Egypt!"
 When Aaron saw this, he built an altar before it; and Aaron made proclamation and said, "Tomorrow shall be a feast to the LORD."
 And they rose up early on the morrow, and offered burnt offerings and brought peace offerings; and the people sat down to eat and drink, and rose up to play.
If the Hebrews were turning en masse to worshipping a false god, rather than reverencing Yahweh in an improper manner, why would they connect the golden calf with the being who had engineered their deliverance from captivity in Egypt, the invisible figure with whom Moses had been conversing?