"The deceit of Muhammad was a fundamental concern for Luther as he feared that a false prophet might tempt Protestant Christians to falter—much as the practice of indulgences had done for Catholics. For a modern man like Luther, the antidote for such deceit was knowledge. The Protestant Reformation was founded on the principle that any Christian could pick up a Bible in the vernacular and make sense of it for him or herself. In like manner, Luther promoted the study of the Qur’an so that Christians would be prepared should they ever have a direct encounter with Islam. Three works illustrate this hermeneutic: his foreword to the Tract on the Religion and Customs of the Turk (1530); his introduction to the German translation of Ricoldo’s Confutatio al-Koran (1542); and the preface to the Swiss publication of the Qur’an (1543)."