At the time of the Reformation the Ottoman Empire was the leading Islamic power in the world. The Caliph or leader of Islam was the Turkish Emperor and to refer to the “Turks” was to refer to Muslims in general. It is interesting to read the opinions of Luther and Calvin on the Turks and what should be done about their threat. Luther observed that the Turks had no cause to invade the lands of others and saw them as God’s chastisement on a degenerate Christendom:
In the first place, the Turk certainly has no right or command to begin war and to attack lands that are not his. Therefore his war is nothing but an outrage and robbery with which God is punishing the world, as he often does through wicked scoundrels, and sometimes through godly people. The Turk does not fight from necessity or to protect his land in peace, as the right kind of ruler does; but, like a pirate or highwayman, he seeks to rob and ravage other lands which do and have done nothing to him. He is God’s rod and the devil’s servant [Isa. 10:5]; there is no doubt about that.Martin Luther: On War Against the Turk
Calvin agrees that the Turks are being used to punish a wicked and superstitious people:
Accordingly, when the Turk now rises up haughtily against us, because he has already vanquished so great a multitude of Christians, we need not be alarmed on that account, as if the power of God were diminished, and as if he had not strength to deliver us. But we ought to consider in how many ways the inhabitants of Greece and of Asia provoked his anger, by the prevalence of every kind of base and shocking licentiousness in those countries, and by the dreadful superstitions and wickedness which abounded. On this account very severe chastisement was needed for restraining the crimes of those who made a false profession of the name of God. Hence came the prosperity of the Turk, and hence was it followed by a shockingly ruinous condition throughout the whole of the east. Yet we see him insolently raising his crest, laughing at our religion, and applauding his own in a strange manner; but still more does he applaud himself, and “sacrifice to his net,” (Habakkuk 1:16,) as we have already said of other infidels.
We ought, therefore, to direct our minds towards the judgments of God, that we may not think that the Turk acquired such extensive dominion by his own strength. But the Lord allowed him greater freedom, for the purpose of punishing the ungodliness and wickedness of men, and will at length restrain his insolence at the proper time. Now, although prosperity is a token of the blessing of God, yet we must not begin with it if we wish to form right views of God himself, as Mahometans and Papists infer from the victories which they have gained, that God is in some respects subject to their control. But when we have known the true God, blessings are added in the proper order to testify his grace and power.Commentaries: Isaiah 36.20
Calvin also decried the attitude of those who thought that the threat from the Turks would never reach them:
…the Jews thought that there was no danger nigh them from nations so remote, as though we were to speak of the Turks at this day, “Oh! they have to fight with other nations: let those who are near them contend with the Turks, for we may live three or four ages in quietness.” We see such indifference prevailing in the present day. Hence the Prophet, in order to deprive the Jews of this vain confidence, says that this nation was near at hand, though coming from remote quarters.Commentaries: Jeremiah 5:15
Luther believed that the best weapon against Islamic expansionism was for Christians to repent and get right with God. He believed the gospel should be embraced more fervently. He taught that the Emperor should take up the war against the Turks and that if called upon by the Emperor, the Christian should join in the fight. Reading his On War Against the Turk can be instructive for how Christians should respond to the jihadi threat in our time.