Blessed Theophylact of Ochrid: On the Lamb of God

"The next day John seeth Jesus coming unto him, and saith, 'Behold the Lamb of God, that taketh away the sins of the world.'" (John 1:29).
He did not say "a lamb," but the lamb for there were many lambs, just as there were many "christs" [anointed ones]. But this is the true Lamb, prefigures by Moses and foretold by Isaiah. (cf Ex 12:21-22, Is 53:4-12) Christ is called the Lamb of God because it is God Who accepts Christ's death for our salvation, and also because it is God Who delivers Christ to death for our sake.... John did not say, "that took away the sin of the world," but, that taketh. He takes away our sins every day, some through Baptism and others through repentance. The lambs slain in the Old Testament could not completely wipe out the sins of even one person; this Lamb wipes out the sin of the whole world.... The sin of the world means universal disobedience: this the Lord completely removed, healing the disobedience of mankind by Himself becoming obedient unto death (Phil 2:8).
+Blessed Theophylact of Ochrid¹, from The Explanation of the Holy Gospel according to John, commentary on John 1:29

¹Theophylact is commemorated as a saint by the Serbian Church. Here we use the more common appellation "blessed".