Question: Isn’t the bronze snake of Numbers 21 an idol? Why would God have Israel make an idol?
Answer: What constitutes an idol is not just any image or sculptured figure. The Israelites were instructed by God to make an image of the two cherubim who attend God’s throne and put them on top of the ark of the covenant to go in the most holy place. But they weren’t idols. What constitutes an idol is an image that is made to represent God Himself and used as part of one’s worship.
The bronze snake on the pole was something God instructed the Israelites to make in order to represent the serpents who were sent by Him to inflict Israel with death. Putting a snake on the pole was representative of killing it. That is why Jesus used this as a picture of his own sacrifice in John 3:14,15: “Just as Moses lifted up the snake in the desert, so the Son of Man must be lifted up, that everyone who believes in him may have eternal life.” The lifted up snake died so the Israelites would not have to. If they put their trust in that they would be healed. The lifted up Jesus died so we would not have to. If we put our trust in him (look to him) we will be forgiven.