The final wound was in the side of Jesus' chest, where, according to the New Testament, His body was pierced by the Lance of Longinus in order to be sure that He was dead. The Gospel of John states that blood and water poured out of this wound (John 19:34). Although the Gospels do not specify on which side He was wounded, it is conventionally shown in art as being on Jesus' right side, though some depictions, show it on the left.
The fact that both water and blood came out demonstrates the extreme stress and trauma He was under. It was so intense that it brought about a condition known as pericardial effusion. This is where fluid builds around the heart and can be fatal. It is often said that this event shows that Jesus died of a broken heart.
The blood and water show us two important aspects of the Lord’s death: the redemptive aspect (blood) and the life-imparting aspect (water).
Because Jesus shed His blood to accomplish redemption for us, we can be forgiven and cleansed of all our sins.
It is clear by historical and medical evidence that Jesus was dead before the wound to his side was inflicted and supports the traditional view that the spear, thrust between his right ribs, probably perforated not only the right lung but also the pericardium and heart and thereby ensured his death.
If the spear pierced through the outer pericardium wall and into the heart, then the watery fluid and blood could have poured out through the wound. It emphasizes the reality of Christ's death and His very humanity. The idea of the Resurrection was very important to the early Christian community. Paul specifically wrote: "If Christ has not been raised, your faith is futile and you are still in your sins." (1 Corinthians 15:17)
The blood and water signify two important matters: redemption (blood) and the imparting of life (water). Jesus' redeeming death accomplished redemption for us, giving us the forgiveness and washing away of our sins that we might have life. As we are cleansed by His blood, we can receive more of the divine life by drinking of Him, the fountain of life.
After the resurrection, Jesus invited Thomas “the doubter” to put his hand also into His side saying, “Reach your finger here…and put it into My side…” (John 20:27). This final piercing of Jesus showed the state of His heart.
"If you desire further proof of the power of this blood, remember where it came from, how it ran down from the cross, flowing from the Master’s side. The gospel records that when Christ was dead, but still hung on the cross, a soldier came and pierced His side with a lance and immediately there poured out water and blood. Now the water was a symbol of baptism and the blood of the holy Eucharist. The soldier pierced the Lord’s side, he breached the wall of the sacred temple, and I have found the treasure and made it my own. So also with the lamb: the Jews sacrificed the victim and I have been saved by it."
From the Catecheses by St. John Chrysostom , bishop
