A sacrifice to be acceptable was required to be blemish free. Jesus is blameless and free of all wrong doings and perfect in all sense.
In today’s Gospel reading, Jesus has just done the miracle of the raising Lazarus from the dead, literally, because he is raised four days after he has died. It is a sensational miracle and everyone gets the wind of this. People start asking questions of this Jesus from Nazareth and his activities and teachings. They start believing. The Leaders of the people are self-serving, and they want to get rid of Jesus, how can they do it. The High Priest, offers a solution, lets handover Jesus as the sacrifice, to appease the Romans, thus saving the nation from the wrath of the Romans. Ironically, and in a Genius way God is getting the people to participate in the sacrifice of Jesus. Just like the Goat sacrificed on the day of Atonement, Jesus now is going to be the Atonement Sacrifice for all people of all times. He is going to unite His people with the God, just like before the Fall.
Jesus is the lamb that takes away the sins of you and me. He washed us clean with his death and resurrection. Now believe this and walk in the light.