This Good Friday, we will hear St. John’s account of the Passion. The entire narrative is moving. But St. John wants one part in particular to stand out to his listeners—Jesus being pierced with a lance. He writes,
When Jesus had taken the wine, he said, “It is finished.” And bowing his head, he handed over the spirit.
Now since it was preparation day, in order that the bodies might not remain on the cross on the sabbath, for the sabbath day of that week was a solemn one, the Jews asked Pilate that their legs be broken and that they be taken down. So the soldiers came and broke the legs of the first and then of the other one who was crucified with Jesus. But when they came to Jesus and saw that he was already dead, they did not break his legs, but one soldier thrust his lance into his side, and immediately blood and water flowed out.
An eyewitness has testified, and his testimony is true; he knows that he is speaking the truth, so that you also may come to believe (19:30-35).
Here John interrupts his own narrative. He speaks directly to his audience, breaks the fourth wall, and forcefully insists that what we just heard was true—Jesus’ side was pierced, and immediately blood and water flowed out.
It is frankly a strange thing to emphasize. John doesn’t call himself out in other parts of the Passion. There was lots of blood throughout that fateful Friday that John lets fall to the ground without commentary. Why flag this outpouring of blood and water?
John supplies the first possibility in the following verses:
For this happened so that the Scripture passage might be fulfilled: Not a bone of it will be broken. And again another passage says: They will look upon him whom they have pierced (vv. 36-37).
The particular drama of Jesus’ wounded side calls to mind many Old Testament prophecies. John himself tells us two, Zechariah 12:10 and Psalm 34:21. But these examples are meant to pique our memory and recall the many other passages John could have legitimately cited: Zechariah 13:1, Isaiah 53:5, Exodus 12:46, Numbers 9:12, Psalm 22:14, and many others.
Prophecy is part of why John emphasizes this moment. But it can’t be the only reason, as John calls out prophecies in other parts of his Gospel without such drama (see 12:38), and he often doesn’t even make explicit the multiple prophetic fulfillments even just within his Passion account.
Maybe the blood and water are so prominent because John thought they were a miracle. Jesus was dead before the soldier’s lance. Death stops the heart, which means blood pressure plummets. As a result, blood (and especially water) doesn’t normally “flow” out of a dead wound with the force of a living body. Indeed, over the centuries since John, some have considered this outpouring miraculous. And, though there were many miracles during Jesus’ ultimate agony (Matthew 27:45-54), this one may have struck John as especially significant.
But although what John records could have been a miracle, modern medical understandings give other, natural possibilities for an outpouring of blood and water.
Crucifixion puts untold strain on the heart, lungs, and muscles. In these situations, the tiny capillary blood vessels throughout our body start to leak fluid out of the bloodstream and into the surrounding tissues. This is all the more likely for one who had suffered scourging (John 19:1), endured multiple blunt force traumas (Mark 15:19), and likely gone without food and water for a significant time (Luke 22:16) even before being nailed to the cross.
Such watery fluid can build up in the lungs and other organs, which itself can be enough to kill. But it’s particularly dangerous when this happens to the heart. The heart is surrounded by a protective membrane called the pericardium, which in such cases can fill up with liquid and add significant pressure to the heart muscle. Even in a healthy person—and especially in a beaten, crucified nomadic preacher—this pressure can overwhelm the heart, squeezing it so it can no longer beat. The little remaining oxygen stops moving, and the heart muscle dies in a massive heart attack.
Many physicians think Jesus died from this or a similar heart attack, because it fits the Gospel evidence better than the other usual ways crucifixion would kill. Jesus died relatively quickly. He was lucid and able to call out multiple times during the end. He knew his death was coming, and he made one final prayer “in a loud voice” (Luke 23:46). These are not typical signs of suffocation or lung issues, which would normally kill the unfortunate crucified Roman. They instead point to the more sudden cardiac death described above. And if this was how Jesus died, there would be at least one pressurized sac full of bloody and watery fluid inside his chest cavity, which would spew out its contents if pierced by a Roman lance.
So postulating a miracle is unnecessary in this case. Modern medical understanding supplies many natural scenarios that possibly and even likely produced the blood and water that John records.
In any event, whatever the reason, John’s attention to this detail of the Passion was inspired by the Holy Spirit, who does know all the prophetic, miraculous, and medical details. And the Spirit calls out the blood and water not merely for prophecy, nor just as a miracle, nor only as medical evidence.
The Spirit’s purpose is much greater. This moment in the Passion captures virtually the whole of Jesus’ plan for salvation and becomes the foundation of the Church.
Jesus Christ came to make us a new creation. St. Paul calls him the new Adam (1 Cor. 15:22-45): Jesus undoes the original sin that enslaved humanity (Rom. 5:12-15). This salvation is won by the entire pascal mystery—but the pivotal moment is right here, on the cross. Here, Jesus declares that it is finished. And here is the first Pentecost, where Jesus hands over his Spirit.
Like a flowing river, grace and salvation are now unstoppable. Jesus has won. He has made the ultimate sacrifice, and the rest of the paschal mystery is now secure, though it is still unfolding. He will march triumphant into hell and break down the ancient gate—for how could Satan’s legions withstand him? He will rise from the tomb—for how could death hold life himself? He will ascend again into heaven, bringing with him all of mankind—for is there any man so worthy of paradise as this new Adam?
Before any of this, blood and water pour out of Jesus’ side. These are the first fruits of his sacrifice. He literally pours his heart out in these streams, which the Fathers teach us give birth to the Church. The water is baptism, which first unites us to Jesus’ death (Rom. 6:3-4). The blood is the Holy Eucharist, which keeps us in communion with him (1 Cor. 10:16).
As St. John Chrysostom tells us, “not without a purpose, or by chance, did those founts come forth, but because by means of these two together the Church consists.” These two sacraments are the start and soul of the Church. In the first moments after his death, Jesus establishes his legacy. His bride, the Church, is born out of the side of the new Adam, just as Eve was born from the side of the first Adam (Gen. 2:18-25).
Just like the rest of the paschal mystery, this still needed time to unfold. The fullness of the Spirit comes fifty-three days later at Pentecost. The depths of this passage’s meaning took additional centuries to unpack. John shows elsewhere in Scripture that he understands the symbolism (1 John 5:6-9); the Fathers of the Church reflected further on this apostolic wisdom, and by the fourth century, there was a clear consensus. John Chrysostom elsewhere expands his earlier words, as he says the Church is born of baptismal water and eucharistic blood from the side of Christ. St. Augustine agrees, saying, “His side was transfixed with a spear, and the sacraments flowed forth, whence the Church was born. For the Church the Lord’s bride was created from his side, as Eve was created from the side of Adam.” Elsewhere Augustine continues, “The gate of life might be thrown open, from whence have flowed forth the sacraments of the Church, without which there is no entrance to the life which is the true life.” St. Ambrose joins in, comparing Eve’s creation from Adam’s side to the Church’s birth from Jesus’ pierced heart.
This wisdom from the Fathers echoed through the following centuries, from Aquinas to Pope John Paul II. Its full meaning is still being discovered through spiritualities like the Divine Mercy. But its biggest legacy is the Church itself, born from this pierced side, and still continuing today—uniting followers to Jesus in the gifts of eucharistic blood and baptismal water ever since that fateful Friday, 2,000 years ago.