The Jews therefore, because it was the preparation, that the bodies should not remain upon the cross on the sabbath day, (for that sabbath day was an high day,) besought Pilate that their legs might be broken, and that they might be taken away. Then came the soldiers, and brake the legs of the first, and of the other which was crucified with him. But when they came to Jesus, and saw that he was dead already, they brake not his legs: But one of the soldiers with a spear pierced his side, and forthwith came there out blood and water. And he that saw it bare record, and his record is true: and he knoweth that he saith true, that ye might believe. For these things were done, that the scripture should be fulfilled, A bone of him shall not be broken. [Exodus 12:46]
God says, “In one house shall it be eaten; you shall not cast the flesh abroad out of the house.” The flesh of Christ and the holy thing of the Lord cannot be cast out. The faithful have no home but the one church. This home, this house of unanimity, the Holy Spirit announces unmistakably in the Psalms: “God who makes men to dwell together of one mind as in a house.”
For the faith of the sacred Scripture sets forth that the Church is not without, nor can be separated nor divided against itself, but maintains the unity of an inseparable and undivided house; since it is written of the sacrament of the passover, and of the lamb, which Lamb designated Christ: "In one house shall it be eaten: ye shall not carry forth the flesh abroad out of the house." Which also we see expressed concerning Rahab, who herself also bore a type of the Church, who received the command which said, "Thou shalt bring thy father, and thy mother, and thy brethren, and all thy father's household unto thee into thine house; and whosoever shall go out of the doors of thine house into the street, his blood shall be upon him." In which mystery is declared, that they who will live, and escape from the destruction of the world, must be gathered together into one house alone, that is, into the Church; but whosoever of those thus collected together shall go out abroad, that is, if any one, although he may have obtained grace in the Church, shall depart and go out of the Church, that his blood shall be upon him; that is, that he himself must charge it upon himself that he perishes; which the Apostle Paul explains, teaching and enjoining that a heretic must be avoided, as perverse, and a sinner, and as condemned of himself. For that man will be guilty of his own ruin, who, not being cast out by the bishop, but of his own accord deserting from the Church is by heretical presumption condemned of himself.
That well-known prophecy likewise was fulfilled: “Not a bone of him shall you break.” For even if this was spoken with reference to the lamb among the Jews, the type preceded for the sake of truth and was, rather, fulfilled in this event. Moreover, that is why the Evangelist cited the prophet. Since he might not seem to be worthy of credence because he was repeatedly making reference to his own testimony, he summoned Moses to testify that this not only did not take place by accident but that it had been foretold in writing from of old. This is the meaning of that famous prophecy: “Not a bone of him shall be broken.”
All such efforts are only of use when they are made within the church’s pale. We must celebrate the Passover in the one house. We must enter the ark with Noah. We must take refuge from the fall of Jericho with the justified harlot, Rahab.
Now next, that the legs of those two were broken, while his [Christ’s] were not. He was already dead. Why this happened was stated in the Gospel itself. It was fitting, you see, to demonstrate by this sign as well that the true point and purpose of the Jewish Passover, which contained this instruction, not to break the lamb’s bones, was to be a prophetic preenactment of his death.
[AD 90] John on Exodus 12:46