The serpent first appears as the tempter in Eden, and remains a symbol of the enemy throughout Scripture. Yet in the wilderness, a bronze serpent lifted on a pole brought healing to all who looked at it.
Jesus said that as Moses lifted up the serpent, so must the Son of man be lifted up — the very symbol of the curse became, at the cross, the means of healing and life.
The Serpent in Scripture
And as Moses lifted up the serpent in the wilderness, even so must the Son of man be lifted up: