Who is the Lamb of God that takes away the sin of the world?
The Lamb of God who takes away the sin of the world is Jesus Christ. John, when he saw Jesus coming, called Him the Lamb of God. Paul also calls Him our Passover, sacrificed for us, showing salvation takes away the stigma of sin.
Les teaches that in I Corinthians 5:7, Paul tells the Gentile church at Corinth to purge out the old leaven, which always spoke of sin and evil. Salvation takes away the stigma of sin, for even Christ our Passover is sacrificed for us. Les connects this to John, who when he saw Jesus coming called Him the Lamb of God which takes away the sin of the world. The Passover Lamb goes all the way back to Exodus 12, where the nation of Israel was in bondage under the heavy hand of the Egyptians. These Old Testament pictures are written for our learning, enhancing what we understand in the New Testament.