St. John the Baptist uses the brazen serpent of Moses to explain the crucifix to Adam. (Antonius Heusler, “Allegory of Salvation”, 1555)
Iconoclasm (opposition to images) is a false tradition of men that was officially condemned by the Church long ago.
Sometimes we miss things in the Bible, though they are right in front of us. Some of our Protestant brethren (mainly Calvinists but some other denominations as well) have an almost obsessive fear of any image associated with worship at all, thinking that all such manifestations are examples of idolatry and undue exaltation of a “graven image”.
In other words, all images whatsoever are collapsed in this wrongheaded mentality into the category of the “graven image” in the Ten Commandments. But the Bible doesn’t take this view at all. Here is one striking example:
Exodus 33:8-10 (RSV) Whenever Moses went out to the tent, all the people rose up, and every man stood at his tent door, and looked after Moses, until he had gone into the tent.  When Moses entered the tent, the pillar of cloud would descend and stand at the door of the tent, and the LORD would speak with Moses.  And when all the people saw the pillar of cloud standing at the door of the tent, all the people would rise up and worship, every man at his tent door.
Note that the pillar of cloud is:
1) a creation (water, if a literal cloud);
2) visual, hence an image;
3) thought to directly represent God Himself.
It’s also a supernatural manifestation, which is a major difference compared to any true idol made by the hands of men; but that would make no difference for those who mistakenly hold that any image whatsoever associated with God is impermissible.
The Bible mentions a pillar of cloud and also a pillar of fire (by night), representing God (see: Ex 13:21-22; 14:24; Num 14:14; Neh 9:12, 19). It doesn't always state that the people worshiped God through the supernatural image-pillars, but we know from Exodus 33:8-10 that it was entirely permissible to do so; certainly not “idolatry.”
The problem (for certain Christians who don't like images) comes when God Himself expressly sanctions such images, and worship in conjunction with them, as here. The same iconoclasts (opposers of images) have to explain away things like the burning bush (Ex 3:2-6), which is not only fire, but also called an “angel of the Lord” (Ex 3:2), yet also “God” (3:4, 6, 11, 13-16, 18; 4:5, 7-8) and “the LORD” (3:7, 16, 18; 4:2, 4-6, 10-11, 14) interchangeably.
An angel is a creation (as are fire and cloud); yet God chose to use a created being and inanimate objects to visibly represent Him. Several similar instances occur in the Old Testament. Moreover, the Jews “worshiped” fire as representative of God in the following passage:
2 Chronicles 7:1-4 When Solomon had ended his prayer, fire came down from heaven and consumed the burnt offering and the sacrifices, and the glory of the LORD filled the temple.  And the priests could not enter the house of the LORD, because the glory of the LORD filled the LORD’s house.  When all the children of Israel saw the fire come down and the glory of the LORD upon the temple, they bowed down with their faces to the earth on the pavement, and worshiped and gave thanks to the LORD, saying, “For he is good, for his steadfast love endures for ever.”  Then the king and all the people offered sacrifice before the LORD.
A related argument, not quite as explicit or direct, but still highly relevant, can be made from use of images in worship that are very closely tied to God, such as the tabernacle, temple, and ark of the covenant. The Bible teaches that Jewish worship was often directed towards these holy and sacred objects; therefore, in a large sense, they represented God Himself.
We know that God made Himself specially present in or near all these material objects. He states repeatedly that He is present above the “mercy seat” on the ark of the covenant, between the two carved cherubim (Ex 25:22; 30:6; Lev 16:2; Num 7:89; 1 Sam 4:4; 2 Sam 6:2; 2 Kg 19:15; 1 Chr 13:6; Ps 80:1; 99:1; Is 37:16; Ezek 10:4; Heb 9:5).
Therefore, we are informed that the Jews would bow before the ark to pray or worship:
Joshua 7:6 Then Joshua rent his clothes, and fell to the earth upon his face before the ark of the LORD until the evening . . . [proceeds to pray in 7:7-8]
1 Chronicles 16:4 Moreover he appointed certain of the Levites as ministers before the ark of the LORD, to invoke, to thank, and to praise the LORD, the God of Israel.
The Jews prayed “toward” Jerusalem and the temple there (more images representing Him or His presence):
1 Kings 8:44 . . . they pray to the LORD toward the city which thou hast chosen and the house which I have built for thy name
Psalm 5:7 But I through the abundance of thy steadfast love will enter thy house, I will worship toward thy holy temple in the fear of thee.
Psalm 138:2 I bow down toward thy holy temple
and give thanks to thy name for thy steadfast love and thy faithfulness; . . .
The temple had all sorts of images in it, giving the lie to the notion that houses of worship couldn't possibly have any images. It had “carved figures of cherubim and palm trees and open flowers” (1 Kg 6:29). From whence comes this notion, then, of bare white-walled churches? Not from Scripture!
Some of the early Calvinists were so fanatical that they smashed not only statues of saints, but also organs, stained glass, even statues of Jesus Christ and crucifixes. They ignored all the distinctions that the Bible plainly makes. We reject such clear biblical teaching at our peril. Iconoclasm (opposition to images) is a false tradition of men that was officially condemned by the Church long ago. Catholic eucharistic worship and devotion hearkens back to this sense of God present through an image.