The Turk at the Door: Luther, Islam, and the Fate of Christendom in the 16th Century

by Adam S. Francisco

In the first half of the 16th century, Western Christendom stood at a crossroads. The Ottoman Empire, led by sultans who claimed the mantle of the caliphate, pressed deep into Europe, while within its own borders the unity of the church and society in general fractured in the wake of the Reformation. The Turk at the Door explores this convergence of empires, ideas, and fears through the eyes of Martin Luther, who viewed the Turks not merely as a geopolitical and religious force but as both the rod of God' s anger and the Devil' s last great assault against Christ' s church. In sermons, tracts, and books Luther offered an interpretation of the times and advice for the future— one that rejected crusade, refined the concept of just war, and rooted Christian endurance in faith rather than violence. Historian and theologian Adam S. Francisco brings to life the world Luther inhabited. Bridging the gap between academic scholarship and accessible narrative, The Turk at the Door reveals a reformer who, amid the terrors of his time, articulated a theology that continues to speak to ours.

112 pages, Kindle Edition

Published July 14, 2026

Reviews

[David Becker · Rating 5 out of 5]

The Turk at the Door: Luther, Islam, and the Fate of Christendom in the 16th Century (1517 Publishing, July 14, 2026, 112 pages) by Adam S. Francisco is the first of two books that I will be reviewing on the subject of Islam. Francisco is Director of Academics at 1517, a California-based Lutheran-oriented parachurch organization. A biography of him adds, “He earned his DPhil from the University of Oxford in 2006 and is the author of a variety of books and articles on topics ranging from Christian apologetics to the history of Christian and Muslim relations, as well as a translator of Martin Luther’s Latin and German writings. In the past, he served on the faculty of Concordia University Irvine and Concordia Theological Seminary. From 2020-2022, he was Dean and Assistant Provost at Concordia University Chicago. He is now cohosts “The Thinking Fellows” and “Faith and Reason Exchange” podcasts. Adam was raised in St. Louis, Missouri, enlisted in the Navy right out of high school, and, after leaving active duty met his wife of 25 years, Rachel. They have four children, a handful of foster children, and too many pets.”

This is a fine five star book on the subject of Martin Luther (1483-1546) and Islam. Luther’s relationship with Islam is its focus. THE TURK AT THE DOOR is based on a far more scholarly and more heavily footnoted (and more expensive) study book, Martin Luther and Islam: A Study in Sixteenth-Century Polemics and Apologetics, that Dr. Francisco authored in 2007. THE TURK AT THE DOOR is intended to be readable as well as authoritative and this 2026 book succeeds in that.

In broad summary, the book depicts Luther as very critical of Islam, while also being critical of popery and Roman Catholicism, sometimes even more so than Islam. Luther also linked Islam to the Apocalypse, which he believed was imminent. (The “Turk” is frequently a term used for an adherent of Islam, given Islam’s sway in Turkey.)

Here’s one of the quotes of Luther:

“These are the people who until now have decried the Turk as the enemy of the Christian name and using this pretext have wrung money from the people and agitated the inhabitants of their territories against the Turks. In order to make war against the Turks, the Roman Satan has bled the world of its money by means of indulgences, annates, and endless sly thievery. What Christians, or rather hellish idols of the Devil!”

At another point, Francisco reports, “Yet Luther reserved his harshest words for the papacy. For at least Islam, he said, openly opposed the Gospel, whereas the papacy corrupted it under the pretense of fidelity. ‘He has initiated wars, murdered kings, trampled nations—all under the banner of Christ,’ Luther declared. ‘Compared to him, Muhammad appears a pure saint.’”

Yet Luther has numerous negative assessments of Islam which are recounted in this book as well. This book is an excellent, reasonably priced source for learning what Luther said about Islam. Francisco notes that he is trying to accurately convey Luther’s views, not necessarily agreeing with Luther on every statement.

[Zachary Cole · Rating 5 out of 5]

Adam S. Francisco’s The Turk at the Door is a timely and insightful study of how Martin Luther understood the Ottoman threat to Christendom. It is both refreshing and, for me, frustrating. Refreshing because it captures Luther’s unwavering insistence that the Christian’s ultimate comfort and focus must remain fixed on the gospel of Jesus Christ—even if the “Turks” should conquer and subjugate Christian lands. Frustrating because I found myself wanting a more crusading, militant response to such a danger. I recognize, however, that this desire may say more about my own instincts than about any shortcoming in Luther’s theology.

In an age when many sense that Western civilization again faces the possibility of being overwhelmed by Islam, Francisco’s book offers a valuable window into how Luther and his contemporaries experienced a similar crisis five hundred years ago. It is a helpful reminder of both the stakes and the proper Christian priority in the face of existential threat.