About the same time Luther made the acquaintance of another opponent of his doctrine of the Lord's Supper, the Silesian Kaspar Schwenkfeld. He also, like his friend Valentin Krautwald, denied the Real Presence; but sought to interpret the words of institution in yet another manner, connecting with his theory of their meaning deeper mystical ideas of the means of salvation in general, which at least in some quarters and to a small extent, have still survived.
In all of them, however—in Carlstadt, Zwingli, Schwenkfeld, and the rest—Luther, as he wrote to his friends at Reutlingen, perceived only one and the same puffed up, carnal mind, twisting about and struggling, to avoid having to remain subject to the Word of God.
His first public declaration against Zwingli's new doctrine was in 1526, in his preface to the Syngramma or treatise of the fourteen Swabian ministers, written, as his opening words express it, 'against the new fanatics, who put forth novel dreams about the Sacrament, and confuse the world.'
Blow upon blow followed in the battle thus commenced. While Oecolampadius was busy composing a reply to the treatise and its preface, by which he in particular had been assailed, Luther proceeded to follow up the attack. The same year he published a 'Sermon on the Sacrament of the Body and Blood of Christ, against the Fanatics;' and in the following spring a larger work with the title 'A Proof that Christ's Words of Institution, "This is My Body," &c., still stand, against the Fanatics.' He concludes the latter with the wish, 'God grant that they may be converted to the truth; if not, that they may twist cords of vanity wherewith to catch themselves, and fall into my hands.' Just then, however, Zwingli had written against him, and to him, and the missive arrived at the moment when he had issued the last-named work. Zwingli wrote in Latin, entitling his tract, 'A Friendly Exposition of the matter concerning the Sacrament,' and sent it with a letter to Luther. These were followed almost immediately by a reply, in German, to Luther's Sermon, under the title of 'A Friendly Criticism of the Sermon of the Excellent Martin Luther against the Fanatics.' Zwingli had scarcely had Luther's last written work in his hands when he replied to it in a new treatise: 'A proof that Christ's words, "This is My Body which is given for you," will for all ages retain the ancient and only meaning, and that Martin Luther in his last book has neither taught nor proved his own and the Pope's meaning;' the title thus indicating that Luther's and the Pope's meaning were one and the same. Oecolampadius at the same time published 'A fair Reply' to Luther's work. These were the writings of the Sacramentarians which reached Luther during the troublous time of the plague at Wittenberg, and filled him with the pain of which we heard him then complain.
Zwingli's doctrine, from the time of its first announcement, had seemed to Luther nothing but a visionary—nay, 'devilish' perversion of the truth and the Word of God. The progress of the controversy, so far from healing the difference between them, tended only to sharpen and intensify it. From the first hour the two Reformers met in opposition, the gulf was already fixed which henceforth divided Evangelical Protestantism into two separate Confessions and Church communities.
This is not the place to pass judgment on the matter in controversy, or to trace minutely the leading points of dogma involved in the dispute. Regarding it, however, by the light of history, it must be acknowledged and avowed that this was no mere passionate quarrel about words alone or propositions of dogmatic and metaphysical interest, but devoid of any religious importance. Even in the attempts to establish points of detail, reference was constantly made, on both sides, to deep questions and views of Christian religion.
Not only did Zwingli and Oecolampadius, in their anti-literal and figurative interpretation of the words of institution, endeavour to support it by Scriptural analogies, more or less appropriate, but in the practical objections they raised, which Luther treated as over-curious subtleties of human reason, they were actuated in reality by motives of a religious character. In their view, a pure and reverential conception of God was inconsistent with the idea of such an offertory of Divine gifts, consisting of material elements and for mere bodily nourishment. Not indeed that Luther, in accepting the words in their literal sense, had become a slave to the letter, in contradiction to the free and lofty spirit in which he had elsewhere accepted the contents of Holy Scripture. The question with him here was about a word of unique importance—a word used by Christ on the threshold, so to speak, of His death for our redemption; and we have already remarked what value he attached to the actual bodily presence indicated by that word, as assuring and imparting salvation to those who partook at His table in faith. No analogies to the contrary, derived from other figurative expressions, would content him, though of course he never denied that such expressions could and did occur throughout the Bible. The text, 'The flesh profiteth nothing,' on which Zwingli primarily relied, Luther understood as referring not to the flesh of Christ, but to the carnal mind of man; though he was careful to declare that it was not the fleshly presence, as such, of our Saviour which gave the Sacrament its value and importance; nor must the feeding of the communicants be a mere bodily feeding, but that the word and promise of Christ were there present, and that faith alone in that word and promise could make the feeding bring salvation. God's glory was therein exalted to the highest, that from His pitying love he made Himself equal with the lowest.
In the doctrine concerning the person of the Redeemer, a point to which the controversy further led, the Church had hitherto affirmed simply a union of the Divine and human natures, each retaining the attributes and qualities peculiar to itself. Luther wished to see in the Man Jesus, the Divine nature, which stooped to share humanity, conceived and realised with deeper and more active fervour. As the Son of God He died for us, and as the Son of Man He was exalted, with His body, to sit at the right hand of God, which is not limited to any place, and is at once nowhere and everywhere. It is true, Luther does not proceed to explain how this body is still a human body, or indeed a body at all. Zwingli, in keeping the two natures distinct, wished to preserve the sublimity of his God and the genuine humanity of the Redeemer; but in so doing, he ended by making the two natures run parallel, so to speak, in a mere stiff, dogmatic formulary, and by an artificial interpretation and analysis of the words of Scripture touching the One Jesus, the Son of God and man.
The manner, however, in which this controversy was conducted on both sides betrays an utter failure on the part of either combatant to apprehend and do justice to the religious and Christian motives, which, with all their antagonism, never ceased to animate the opposite party. Luther's attitude towards Zwingli we have already noticed. We have seen how his zeal, in particular, prompted him too often to see in the conduct of individual opponents simply and solely the dominating influence of that spirit, from which certain pernicious tendencies, according to his own convictions, proceeded and had to be combated. Thus it was in this instance. It was all visionary nonsense, nay, sheer devilry, and be attacked it in language of proportionate violence. From Zwingli a different attitude was to be expected, from the amicable titles of his treatises and the personal correspondence with Luther which he himself invited. He adopted here for the most part, as in other matters, a calm and courteous tone, and exercised a power of self-restraint to which Luther was a stranger. But with a lofty mien, though in the same tone, he rejected Luther's propositions, as the fruit of ludicrous obstinacy and narrowness of mind, nay, as a retrograde step into Popery. His letter, moreover, embittered the contest by importing into it extraneous matter of reproach, such as, in particular, Luther's conduct in the Peasants' War. Luther had reason to say of him, 'He rages against me, and threatens me with the utmost moderation and modesty.' Zwingli's later replies evince a straightforwardness we miss in the earlier ones, but they are marred by much rudeness and coarseness of language, and display throughout a lofty self-consciousness and a triumphant assurance of victory.
Luther, after reading the last-mentioned treatises of Zwingli and Oecolampadius, resolved to publish one answer more, the last; for Satan, he said, must not be suffered to hinder him further in the prosecution of other and more important matters. At this time he was particularly anxious to complete his translation of the Bible, being now hard at work with the books of the Prophets. His answer to Zwingli grew ultimately into the most exhaustive of all his contributions to the dispute. It appeared in March 1528 under the title of 'Confession concerning the Lord's Supper.' He went over once more all the most important questions and arguments which had formed the subject of contention, expounded his ideas more fully on the Person and Presence of Christ, and explained calmly and impressively the passages of Scripture relating thereto. He concluded with a short summary of his own confession of Christian faith, that men might know, both then and after his death, how carefully and diligently he had thought over everything, and that future teachers of error might not pretend that Luther would have taught many things otherwise at another time and after further reflection.