On the one hand, the defeat of King Sigismund at
Nicopolis in 1396 and in particular the conquest of Constantinople by Muhammad
(Mehmed) II in 1453 intensified the effort to investigate the Ottoman Empire,
the Turks and their religion.
The Turks posed a military threat to the Holy Roman Empire of the German Nation, as Belgrade had already fallen to the expansion of the Ottoman Empire in 1521, and Sultan Suleiman I the "Magnificent" and his troops had laid siege to Vienna for the first time in 1529.
Christians were gripped by fear, and the Noon Bells introduced by Pope Calixtus III were mandated by the Imperial Government in 1523. There were even ecumenical sermons decrying the Turks. On the other hand, the Muslims presented the Christian religion with the question: what did the belief system actually mean; was Islam an alternative – if albeit inferior – religion or, in view of the common heritage shared with Judaism and Christianity, a perfidious cult?
The Turks were considered dangerous, possibly superior, military opponents. So they were viewed as a kind of divine retribution as well. Luther also echoes this premonition that the end times were imminent. Like the Lutheran theologian Mylius, who called the Koran "a desert and cesspit of all lies and falsehoods", Luther posited that any Turk "who earnestly believes in the Koran" is not worth being considered a human being. (WA 53, 388,33)
Alternatively, they should be regarded as humans if they were mere heretics and therefore "half Christians", or if they were following reason in the areas of medicine, astronomy and philosophy. (WA 53, 389,31-390,5).
This could be viewed as a similarity to his earlier and later writings on the Jews: cordial advances for as long as the possibility of conversion remained promising, but then a complete volte face. The common heritage shared by Christianity, Judaism and Islam also leads to characteristic parallelism and projections, in which the "non-Evangelical legality" of Islam is equated with the papist religion, stating that the latter must be defeated first in order to confront Islam with unadulterated scripture.
Luther almost uniformly perceives the Ottoman threat as a divine punishment for the papists and their heretical approach to God's Word. But Luther rejected any notion of a Crusade, upholding his belief that the Word should prevail in any religious dispute. He therefore advocated – and engaged in – diligent study of the Koran, Islam's holy book, instead of judging the Turks based on their customs alone.
He considered it essential to examine the attraction of the Turkish religion, so as to present the superiority of the Christian faith. Luther responded to the military threat presented by the Turks in his writings that included
On War Against the Turk (WA 30 II, 107-148), in which – following his dogma of the "Two Governments" – he emphasised the duty of the ruling classes to protect the Empire against the Turkish invasion. This duty is also emphasised in Article 16 of the Augsburg Confession (CA 16).
Literature: Thomas Kaufmann, "Türckenbüchlein", Zur christlichen Wahrnehmung "türkischer Religion" in Spätmittelalter und Reformation (Forschungen zur Kirchen – und Dogmengeschichte 97), Göttingen 2008
Reformation and Islam