Its worth keeping in mind that ‘close’ is very different from being contradictory.

though none of them are exact actual quotes, and a few of them are things that Luther would have disagreed with!

Alleged Luther quote #1:

If I believed the world were to end tomorrow, I would still plant a tree today.

Luther didn’t say this. For a thorough discussion, see Martin Schloemann, Luthers Apfelbäumchen: Ein Kapitel deutscher Mentalitätsgeschichte seit dem Zweiten Weltkrieg (Göttingen: Vandenhoeck & Ruprecht, 1994), 246-251 (via Frederick Gaiser, HT: Garrett Lee). Schloemann argues that it’s not only something Luther didn’t say but wouldn’t say, unless it was put into a Christocentric eschatology emphasizing “creaturely service of neighbor and world.”

Alleged Luther quote #2:

The maid who sweeps her kitchen is doing the will of God just as much as the monk who prays—not because she may sing a Christian hymn as she sweeps but because God loves clean floors.

The Christian shoemaker does his Christian duty not by putting little crosses on the shoes, but by making good shoes, because God is interested in good craftsmanship.

Luther didn’t say this. As with the quote from the first example, Gaiser argues that it doesn’t sit very well with Luther’s actual views on vocation. The idea that God is pleased with our work because he likes quality work “would be the American work-ethic version of vocation, theologically endorsing work as an end in itself. In the hands and mouth of a modern boss, good craftsmanship and clean floors (or a clean desk or a signed contract) to the glory of God could be a potent and tyrannical tool to promote the bottom line. . . . [W]hat marks Luther’s doctrine of vocation is the insistence that the work is done in service of the neighbor and of the world. God likes shoes (and good ones!) not for their own sake, but because the neighbor needs shoes. . . .”

Alleged Luther quote #3:

If I profess with the loudest voice and clearest exposition every portion of the Word of God except precisely that little point which the world and the devil are at that moment attacking, I am not confessing Christ, however boldly I may be professing Him. Where the battle rages there the loyalty of the soldier is proved; and to be steady on all the battle front besides, is mere flight and disgrace if he flinches at that point.

Luther didn’t say this exactly, but this one is closer. Denny Burk looked into this one:

Most writers quote other writers’ use of the term. The few that credit an original source cite a letter published in the Weimar edition of Luther’s works [D. Martin Luther’s Werke : kritische Gesamtausgabe (Weimarer Ausgabe) : [3. Band] Briefwechsel, ed. (Weimar: H. Böhlaus Nachfolger, 1933), 81-82].

Here’s a rough translation:

“Also it does not help that one of you would say: ‘I will gladly confess Christ and His Word on every detail, except that I may keep silent about one or two things which my tyrants may not tolerate, such as the form of the Sacraments and the like.’ For whoever denies Christ in one detail or word has denied the same Christ in that one detail who was denied in all the details, since there is only one Christ in all His words, taken together or individually.”

As you can see, this does not match the first quotation, though the sentiments described in the former are similar to the latter.

Alleged Luther quote #4:

I’d rather be ruled by a wise Turk than by a foolish Christian.

Luther didn’t say this one, and wouldn’t have. Gene Veith offers an extended analysis. Here is his conclusion:

These statements by Martin Luther and their context within the various documents he wrote are more than sufficient to convince reasonable readers that Luther would never have uttered the falsely attributed quote and would never regard as a preferable desire or choice to be ruled by a Turk. [It] is not “Luther-esque” and in fact, it is diametrically opposed to the position on which we know from his writings Luther firmly stood.

Alleged Luther quote #5:

Justification is the article by which the church stands and falls.

This one is pretty close.

The first use of this exact Latin phrase (justificatio est articulus stantis et cadentis ecclesiae) seems to be by Lutheran theologian Balthasar Meisner—born 40 years after Luther’s death—who said that it was a “proverb of Luther” (Anthropôlogia sacra disputation 24 [Wittenberg: Johannes Gormannus, 1615]).

In 1618 Reformed theologian Johann Heinrich Alsted wrote articulus iustificationis dicitur articulus stantis et cadentis ecclesiae (in Theologia scholastica didacta [Hanover, 1618], p. 711)— “The article of justification is said to be the article by which the church stands or falls.”

We don’t have record of Luther using the exact phrase, but very close: quia isto articulo stante stat Ecclesia, ruente ruit Ecclesia—“Because if this article [of justification] stands, the church stands; if this article collapses, the church collapses.” (WA 40/3.352.3)

So the famous version is more like a summary of paraphrase of his actual quote.

Alleged Quote #6:

Here I stand; I can do no other.

Diarmaid MacCulloch, in his magesterial work on the Reformation, says this is the “most memorable thing Luther never said.” Many scholars believe that it was first inserted at the end of Luther’s speech by the first editor of his collected works, Georg Rörer (1492-1557).

*** Re: #6:

“These words are given in German in the Latin text upon which this translation is based. There is good evidence, however, that Luther actually said only: ‘May God help me!’ Cf. Deutsche Reichstagsakten, Vol. II: Deutsche Reichstagsakten unter Kaiser Karl V (Gotha, 1896), p. 587.”

Source: Martin Luther, Luther’s Works, Vol. 32: Career of the Reformer II, ed. Jaroslav Jan Pelikan, Hilton C. Oswald, and Helmut T. Lehmann (Philadelphia: Fortress Press, 1999), 113 n8.

*** Re: #2 The second alleged quote is actually quite close to something he says in his Large Catechism regarding the fourth commandment (I could see how it could be simplified, embellished and twisted to get to the quote you have above with a few subtle changes over time):

“Should not the heart, then, leap and melt for joy when going to work and doing what is commanded [by honoring one’s father and mother], saying: Lo, this is better than all holiness of the Carthusians, even though they kill themselves fasting and praying upon their knees without ceasing? For here you have a sure text and a divine testimony that He has enjoined this, but concerning the other He did not command a word. But this is the plight and miserable blindness of the world that no one believes these things; to such an extent the devil has deceived us with false holiness and the glamour of our own works….

… If this truth, then, could be impressed upon the poor people, a servant-girl would leap and praise and thank God; and with her tidy work for which she receives support and wages she would acquire such a treasure as all that are esteemed the greatest saints have not obtained. Is it not an excellent boast to know and say that, if you perform your daily domestic task, this is better than all the sanctity and ascetic life of monks? And you have the promise, in addition, that you shall prosper in all good and fare well. How can you lead a more blessed or holier life as far as your works are concerned? For in the sight of God faith is what really renders a person holy, and alone serves Him, but the works are for the service of man.” -Martin Luther, The Large Catechism, The Fourth Commandment