4 Charity therefore we commend; charity this Epistle commends. The Lord, after His resurrection, what question put He to Peter, but, “Do you love me?” And it was not enough to ask it once; a second time also He put none other question, a third time also none other. Although when it came to the third time, Peter, as one who knew not what was the drift of this, was grieved because it seemed as if the Lord did not believe him; nevertheless both a first time and a second, and a third He put this question.
Thrice fear denied, thrice love confessed. Behold Peter loves the Lord. What is he to do for the Lord? For think not that he in the Psalm did not feel himself at a loss what to do: “What shall I render unto the Lord for all the benefits He has done unto me?” He that said this in the Psalm, marked what great things had been done for him by God; and sought what he should render to God, and could find nothing. For whatever you would render, from Him did you receive it to render.
And what did he find to offer in return? That which, as we said, my brethren, he had received from Him, that only found he to offer in return. “I will receive the cup of salvation, and will call upon the name of the Lord.” For who had given him the cup of salvation, but He to whom he wished to offer in return? Now to receive the cup of salvation, and call upon the name of the Lord, is to be filled with charity; and so filled, that not only you shall not hate your brother, but shall be prepared to die for your brother.
This is perfect charity, that you be prepared to die for your brother. This the Lord exhibited in Himself, who died for all, praying for them by whom He was crucified, and saying, “Father, forgive them, for they know not what they do.” But if He alone has done this, He was not a Master, if He had no disciples. Disciples who came after Him have done this. Men were stoning Stephen, and he knelt down and said, “Lord, lay not this sin to their charge.” He loved them that were killing him; since for them also he was dying.
Hear also the Apostle Paul: “And I myself,” says he, “will be spent for your souls.” For he was among those for whom Stephen, when by their hands he was dying, besought forgiveness. This then is perfect charity. If any man shall have so great charity that he is prepared even to die for his brethren, in that man is perfect charity. But as soon as it is born, is it already quite perfect? That it may be made perfect, it is born; when born, it is nourished; when nourished, it is strengthened; when strengthened, it is perfected; when it has come to perfection, what says it?
“To me to live is Christ, and to die is gain. I wished to be dissolved, and to be with Christ; which is far better: nevertheless to abide in the flesh is needful for you.” For their sakes he was willing to live, for whose sakes he was prepared to die.
Source: Homilies on the First Epistle of John (New Advent)