What was the purpose of the brazen serpent Moses lifted up?
The brazen serpent was lifted up so that the Israelites, dying from snakebites, could look upon it and have their sin judged. Scripture uses brass to denote judgment, and the serpent prefigured the cross, where the reality of sin's judgment was accomplished.
Les explains that all through Scripture brass speaks of judgment. When Israel was dying from snakebites, God told Moses to erect a brazen serpent, and it judged their sin as they looked at it. This pointed to the cross, where the reality of the work was that sin was judged. The same principle appears in the brazen altar, wood covered with brass, and in the laver of cleansing made from the women's looking glasses, filled with water, showing the need for cleansing.