The fourteenth chapter and the two that follow it contain the beautiful sermon delivered by Christ after the celebration of the Last Supper, on the threshold of His suffering and His departure from His beloved disciples. With this sermon He wanted to comfort and strengthen them both against the present sadness occasioned by His departure and against the suffering they would endure because of the devil, the world, and their own conscience. Indeed, here we find the best and most comforting sermon preached by Christ while on this earth. And St. John should be praised above the other evangelists for recording and transmitting it to Christendom for their comfort, as a jewel and treasure not purchasable with the world’s goods. It would be deplorable had we been deprived of it and had it not been handed down to us.
This sermon contains the most precious and cheering consolation, the sweetest words of Christ, the faithful and beloved Savior, words of farewell to His disciples as He is about to leave them, words such as no man on earth is able to employ toward his dearest and best friends. They show how He provides for them out of the pure, ineffable, burning love of His heart, and how He is concerned about them far more sincerely than any man is about the greatest need and danger of his most intimate friend. In His concern for them He forgets His own anguish and anxiety, which must have filled His heart at this time, as He Himself confided to His disciples: “My soul is very sorrowful, even to death” (Matt. 26:38). Moreover, His battle against death and the devil had now reached its highest point. Here Christ richly poured out His great and heartfelt comfort, which is the property of all Christendom and which men should long for in all troubles and afflictions.
Furthermore, here we find the true, chief high articles of Christian doctrine established and set forth in the most powerful manner. Nowhere else in Scripture are they to be found side by side in this way. For example, the doctrine of the three distinct Persons in the Holy Trinity, particularly of the divine and human natures in the eternally undivided Person of the Lord Christ; also the doctrine of justification by faith and of the real comfort for consciences. The evangelist discourses here on sublime themes such as these: how man may safely encounter and embrace God; how he may be justified before God and be assured of His mercy; how he may rely on this mercy with all his heart and defy all sorts of trials and temptations. And all these doctrines are supported here so clearly and convincingly that one can powerfully strike down all heretics and schismatic spirits, no matter what their names are.
Therefore it is surely fitting and proper that this sermon be diligently studied and considered in Christendom. To this end these three chapters have been assigned since time immemorial as Gospel lessons between Pentecost and Easter. Whoever wanted to could devote himself to a thorough study of them during this season.1 We, too, have undertaken this task, resolved to interpret these chapters for the common man, but especially to defend and preserve the true and pure doctrine of Christ and of the Christian faith against the vile mobs of the devil, whether present or future. And herewith we wish to commend this proclamation to pious Christians as their highest and most precious treasure and consolation, that they may learn it and preserve it with diligence.
Luther, M. (1999, c1961). Vol. 24: Luther's works, vol. 24 : Sermons on the Gospel of St. John: Chapters 14-16 (J. J. Pelikan, H. C. Oswald & H. T. Lehmann, Ed.). Luther's Works (24:7). Saint Louis: Concordia Publishing House.