How is looking to Christ like the Israelites looking at the brazen serpent?
The brazen serpent prefigured Christ's work: brass symbolizes judgment, and the serpent was made of brass because it was a subject of judgment. When Israelites looked, God judged their sin and they were healed. Likewise, looking to Christ—who took our sin, on whom God's judgment fell—brings healing through forgiveness, salvation, and justification.
Les explains that the brazen serpent was another foreview of the work of Christ. Because brass always speaks of judgment in the Bible, the serpent had to be made of brass—it was a subject of judgment. When the Israelites looked at that brazen serpent, God judged their sin, and they were healed. In the same way now, when we look to Christ, who took our sin and on whom God's judgment fell, we are healed of our sin problem in what is called forgiveness, salvation, and justification. Les also ties this to Israel's wilderness experience, noting these things were written for our admonition, so that we take heed lest we fall.
And Moses made a serpent of brass, and put it upon a pole, and it came to pass, that if a serpent had bitten any man, when he beheld the serpent of brass, he lived.
And as Moses lifted up the serpent in the wilderness, even so must the Son of man be lifted up:
See the restNeither let us tempt Christ, as some of them also tempted, and were destroyed of serpents.