The next day John saw Jesus coming toward him and said, “Look! The Lamb of God who takes away the sin of the world! (John 1:29 NLT)
John the Baptist had been preaching by the Jordan river preparing peoples’ hearts for the Messiah. His theme was repent and turn to God. He knew the time was near when the Son of God would appear. He was preaching that the Messiah would be the Lamb of God and take away the sins of the world. When John saw Jesus, he recognized immediately that Jesus was the Lamb of God and pointed Jesus out to the crowd.
From the beginning of sin in this world, people had been sacrificing lambs for their sins. During the Passover (Exodus 12:5) the lamb was to be without blemish. These lambs were symbolic of the Lamb of God that would take away the sins of the World.
Jesus is the Lamb of God that takes away our sins.