Christ taught: “And whosoever shall exalt himself shall be humbled.” Luther teaches: “What I teach and write remains true even though the whole world should fall to pieces over it”[Weimar, Vol. 18, Pg. 401].
Luther Exposing the Myth says their stated purpose is to show that "from Luther’s own words we shall see him for what he really was, that is a rebellious apostate, who abandoned the faith and led many into apostasy from God under the guise of “reformation” in order to follow his perverse inclinations." With this quote, they attempt to show Christ taught one should be humble, while Luther pridefully claims his teachings are true "even though the whole world should fall to pieces over it."
Luther, Exposing the Myth cites "Weimar, Vol. 18, Pg. 401." This page can be found here. It's the last page from the treatise entitled, "Ein Sendbrief von dem barten Büchlein wider die Bauern" (1525). In English, it's referred to as "Circular Letter on the Severe Booklet Against the Peasants" or "An Open Letter on the Harsh Book Against the Peasants." In the English LW set, the quote can be found in LW 46:84, and also in the earlier Works of Martin Luther IV:281.
The possibilities the author of Luther, Exposing the Myth actually reading any of the above sources is rather slim. It's more probable the quote was taken from Peter F. Wiener's Martin Luther, Hitler's Spiritual Ancestor, page 28. There the author states,
Luther knew that he was superior to any man or saint. “St. Augustine or St. Ambrosius cannot be compared with me.” “They shall respect our teaching which is the word of God, spoken by the Holy Ghost, through our lips”. “Not for a thousand years has God bestowed such great gifts on any bishop as He as on me” (E61, 422). “God has appointed me for the whole German land, and I boldly vouch and declare that when you obey me you are without a doubt obeying not me but Christ” (W15, 27). “Whoever obeys me not, despises not me but Christ.” “I believe that we are the last trump that sounds before Christ is coming”. “What I teach and write remains true even though the whole world should fall to pieces over it.” (W18, 401). “Whoever rejects my doctrine cannot be saved.” “Nobody should rise up against me”.Wiener probably got the quote from reading Roman Catholic historian Hartmann Grisar. Grisar cites the same quote on page 284 of Martin Luther His Life and work, and also on page 208 of Luther volume 2.
This quote comes from Luther's writings during the peasants war. Luther's statements about the peasants and rulers were being maligned from friend and foe alike. In the writing in question, Luther offers a public explanation for his views. LW explains,
In this treatise Luther defends at length the views he had advanced in Admonition to Peace and Against the Robbing and Murdering Hordes of Peasants. The peasants should not have rebelled, for the duty of a Christian is to suffer injustice, not to seize the sword and take to violence. His opponents, Luther says, can criticize him as they will, but they cannot change the fact that in the light of God’s word the rebellious peasants deserved to be put to death and to have their insurrection suppressed by the full force of the governing authorities. Force was the only language the rebels understood. Furthermore, Luther argues, his critics’ sudden surge of sympathy for the defeated peasants marks them as secret rebels against God and state.
But if there was no excuse for the peasants to rebel, neither was there any excuse for the rulers to indulge their lust for rebel blood. Here, however, Luther is not moved by any sense of “fair play.” He disclaims responsibility for the wanton cruelty of the rulers, which, he says, is nothing but the flagrant abuse by the princes of their God-given office. Such cruelty is as reprehensible and sinful as insurrection. The princes, he says, will surely reap God’s wrath for such conduct. [LW 46:61]
An important question to ask is exactly what Luther was referring to when he said "What I teach and write remains true even though the whole world should fall to pieces over it." The quote in question comes from the very last paragraph of the treatise:
This, dear sir and friend, is my answer to your letter. I hope that I have more than satisfied you. If anyone is not satisfied, let him remain, in God’s name, wise and prudent, righteous and holy; and let me remain a fool and a sinner. I wish that they would leave me in peace; but they will not win, and what I teach and write will still be true, even though the whole world were to burst. If anyone wants to be peculiar, I, too, shall be peculiar, and we shall see who is right in the end. [LW 46:83-84]Interestingly, the very same sort of comment can be found in the beginning of the treatise:
Here I do not want to hear or know about mercy, but to be concerned only about what God’s word requires. On this basis, my little book was and remains fight, even though the whole world take offense at it. [LW 46:56]What is it that God's word requires?
God’s word says, “My son, fear the Lord and the king; if you do not, disaster will suddenly come upon you” [Prov. 24:21–22]. And in Romans 12 [13:2], “Whoever resists God’s authority will incur judgment.” Why is not St. Paul merciful? If we are to preach God’s word, we must preach the word that declares his wrath, as well as that which declares mercy. We must preach of hell as well as heaven, and help extend God’s word and judgment and work over both the righteous and the wicked, so that the wicked may be punished and the good protected.[LW 46:66]
In this treatise, Luther offers a thorough defense of his earlier writings about the peasants. This is not the place to restate all those arguments, the interested reader can seek them out.
What concerns me is the particular interpretation placed on Luther's words by his various critics. Luther, Exposing the Myth sees the statement as prideful. Peter F. Wiener interprets the statement as a claim to superiority. What the context though shows is a carefully argued defense based on a Scriptural principle that the government bears the sword. I would simply ask Luther's critics to explain Romans 13 before charging him with either pride or a superiority complex:
Every person is to be in subjection to the governing authorities. For there is no authority except from God, and those which exist are established by God. Therefore whoever resists authority has opposed the ordinance of God; and they who have opposed will receive condemnation upon themselves. For rulers are not a cause of fear for good behavior, but for evil. Do you want to have no fear of authority? Do what is good and you will have praise from the same; for it is a minister of God to you for good. But if you do what is evil, be afraid; for it does not bear the sword for nothing; for it is a minister of God, an avenger who brings wrath on the one who practices evil. Therefore it is necessary to be in subjection, not only because of wrath, but also for conscience’ sake. For because of this you also pay taxes, for rulers are servants of God, devoting themselves to this very thing. Render to all what is due them: tax to whom tax is due; custom to whom custom; fear to whom fear; honor to whom honor.
As an aside, one could argue that those rulers who slew the peasants were overly harsh, so Luther was simply helping tyrants be tyrannical. Such an argument though would be at the expense of Luther's stated position:
I made it plain that I was speaking of those who were first approached in a friendly way, and would not respond. All my words were directed against the obdurate, hardened, blinded peasants, who would neither see nor hear, as anyone may see who reads them; and yet you say that I advocate the merciless slaughter of the poor captured peasants. If you are going to read books this way and interpret them as you please, what book will have any chance with you? Therefore, as I wrote then so I write now: Let no one have mercy on the obstinate, hardened, blinded peasants who refuse to listen to reason; but let everyone, as he is able, strike, hew, stab, and slay, as though among mad dogs, so that by so doing he may show mercy to those who are ruined, put to flight, and led astray by these peasants, so that peace and safety may be maintained. It is better to cut off one member without mercy than to have the whole body perish by fire, or by disease [Matt. 5:29–30]. How do you like that? Am I still a preacher of the gospel who advocates grace and mercy? If you think I am not, it makes little difference, for you are a bloodhound, and a rebellious murderer and destroyer of the country, you and your rebellious peasants, whom you are flattering in their rebellion.[LW 46:73]
I earnestly ask you, and everyone, to read my book fairly, and not run through it so hurriedly. Then you will see that I was advising only Christian and pious rulers, as befits a Christian preacher. I say it again and for the third time. I was writing only for rulers who might wish to deal in a Christian or otherwise honest way with their people, to instruct their consciences concerning this matter to the effect that they ought to take immediate action against the bands of rebels both innocent and guilty. And if they struck the innocent, they were not to let their consciences trouble them, since they were by the very act confessing that they were bound to do their duty to God. Afterward, however, if they won, they were to show grace, not only to those whom they considered innocent, but to the guilty as well.Luther goes on to further describe such rulers:
But these furious, raving, senseless tyrants, who even after the battle cannot get their fill of blood, and in all their lives ask scarcely a question about Christ—these I did not undertake to instruct. It makes no difference to these bloody clogs whether they slay the guilty or the innocent, whether they please God or the devil. They have the sword, but they use it to vent their lust and serf-will, I leave them to the guidance of their master, the devil, who is indeed leading them.
Why should I write for scoundrels and hogs like that? The Scriptures call such people “beasts” [Titus 1:12], that is, “wild animals,” such as wolves, boars, bears, and lions, and I shall not make men of them; and yet we must put up with them, when God plagues us with them. I had two fears. If the peasants became lords, the devil would become abbot; but if these tyrants became lords, the devil’s mother would become abbess. Therefore I wanted to do two things: quiet the peasants, and instruct the pious lords. The peasants were unwilling to listen, and now they have their reward; the lords, too, will not hear, and they shall have their reward also. However, it would have been a shame if they had been killed by the peasants; that would have been too easy a punishment for them. Hell-fire, trembling, and gnashing of teeth [Matt. 22:13] in hell will be their reward eternally, unless they repent.[LW 46:83-84]