Lamb of God

The title is found just twice in the New Testament, in the Gospel according to John:

The next day he [John the Baptist] saw Jesus coming toward him and said, "Behold, the Lamb of God, who takes away the sin of the world." (John 1:29)

The next day John was there again with two of his disciples, and as he watched Jesus walk by, he said, "Behold, the Lamb of God." (John 1:35f)

But the image of Christ as lamb is very prominent in Revelation, where Christ 28 times is referred to as Lamb and also appears in Acts 8:32, 1 Cor 5:7 (implied) and 1 Peter 1:19.

The title has to be understood against the background of:

1. the paschal lamb[?] of the Old Testament whose blood protected and saved the Isrealites (Exodus 12). This link is explicit in 1 Cor 5:7. For Paul Christians are saved by Christ as their true paschal lamb.
2. the Old Testament practice of sin offerings. Lambs could be used in these offerings (e.g. Lev 4:32-34 and 5:6). This link is strongly suggested by John 1:29 and 1 Peter 1:19. Like the sin of a person could be forgiven through the offering and the pouring out of the blood of an "unblemished" lamb (cf. Lev 4:32) so Christians would be freed from sin by the blood of Christ as umblemished lamb.
3. the suffering servant of Isaiah 53 who "like a lamb led to the slaughter" (53:7) was silent and "gives his life as an offering for sin" (53:10). This link is explixit in Acts 8:32 and strengthens the idea of Christ as sin offering.

Revelation uses another Greek word for Lamb and so the apocalyptic[?] picture of a ruling and victorious lamb probably should not be read into the title "Lamb of God" in John.