"And looking upon Jesus as he walked, he saith, Behold the Lamb of God!" (John 1:36)
As he spoke to two of his followers, John the Baptist was, in effect, telling them that they should henceforth leave him to follow Jesus. "And the two disciples heard him speak, and they followed Jesus" (John 1:37). On the previous day, when John had first seen Jesus coming, he had said, apparently to all his disciples, "Behold the Lamb of God, which taketh away the sin of the world" (John 1:29).
This is the first use of the word "lamb" in the New Testament, and it is significant that it refers here to the Lord Jesus as the one great sacrifice for our sins. He is called "the Lamb" 30 more times in the New Testament, the final time no longer viewing Him on the altar but on His eternal throne (Revelation 22:3). Yet, even on His throne as our King, He is still the Lamb, and we can never ever forget that He once died for us that we might live with Him.
Long before this, Isaac once asked his father, "Where is the lamb for a burnt offering?" Abraham answered, "God will provide himself a lamb" (Genesis 22:7-8). God did just that 2000 years later, when Christ, "the Lamb slain from the foundation of the world" (Revelation 13:8), "came into the world to save sinners" (1 Timothy 1:15).
Then when God was ready to set His people free in ancient Egypt, He told them to place the shed blood of a spotless lamb on the doorpost of each home and said, "When I see the blood, I will pass over you" (Exodus 12:13). In fulfillment of all these ancient sacrifices and types, the once-for-all Lamb of God came, and "Christ our passover is sacrificed [even] for us" (1 Corinthians 5:7).
Now, like John's disciples, it surely compels us, in the very depths of our souls, to "behold the Lamb of God" and follow Him. HMM