Martin Luther’s Sermons and Postils
Authors: Frymire John M. 
Published: March 2017

For Martin Luther the sermon was not simply an exercise in which a preacher expounded on the biblical text, taught moral lessons, and reprimanded listeners for their shortcomings. The sermon meant far more than that. Preaching was God’s voice speaking through the minister. Hearing God’s promise of salvation was far more effective than reading it. In terms that echoed medieval theories of demonology, which posited that reading biblical passages aloud exorcized the air, Luther insisted that Satan fled the spoken word of God even if the written form bothered him not a whit. The sermon was the site where Christ confronted Satan in eschatological combat. Minsters made Christ really present from their pulpits and, through their preaching of God’s word, provided the means through which the Holy Spirit “worked,” literally, upon the auditor. Luther’s sense of the sermon was spiritual and physical to the extent that he considered preaching quasi-sacramental in the medieval sense of the opus operatum.

Luther’s theology of preaching was among the most original of his discoveries, but he did not invent the sermon. For 1,500 years Christianity had spread among overwhelmingly illiterate populations, and the oral exposition of scripture was part of Christian services early on. Patristic theologians such as Augustine had preached extensively and left a corpus of manuscript sermons that influenced later exegetes. The advent of printing in the mid-15th century spread the homilies of medieval preachers and their patristic forerunners as never before. Especially popular were postils, model sermons for Sundays and festival days that were available in Latin and vernacular versions. Printing, the spread of the Mendicant preaching orders, improved clerical education, and increasing lay literacy all combined to produce a late medieval preaching renaissance. Martin Luther was born into this renaissance just as he became a trained professional in its tradition. When he died in 1546 he was no longer a late medieval Augustinian, but he had been a preacher by trade for nearly forty years.

Luther preached constantly. None of his other duties took as much of his time. About 2,300 of his sermons survive, which, based on his preaching schedule, represent about half of the sermons he preached. Sermons take up some thirty volumes—that is, one-third—of the Weimar edition (WA) of his works. No other genre in his corpus comes close. The same can be said of the printing and impact of his sermons: none of Luther’s contemporaries came close either. Unlike many of those contemporaries, however, the most significant preacher in early modern Europe never wrote a treatise on how to preach. Luther never produced a comprehensive work of dogmatics either, and for the same reason: the incredibly gifted theologian was not a gifted systematician. Several of Luther’s greatest admirers noted as much, warning future preachers that unlike Luther, whose sermons tended to drift hither and yonder, they should stick to the main roads.

Determining what sermons Luther actually delivered is nettlesome because it hinges on the types and numbers of texts that have come down to us. The issue is always the state of the sources. Thus, the rudiments of Luther’s sermons and postils as genres are presented, and select issues of manuscript and print production that shape our understanding of what Luther preached and how his ideas were received are examined.