A lot of things contributed to the spread of the Gospel at the time of the Reformation. Pervasive knowledge of the corruption of “the Church”. The printing press. The willingness (and newfound ability) of the Reformers to reach back ad fontes (“to the original sources”). One of the most important, however, was Martin Luther’s decision to write in his native tongue, German, instead of in Latin:
Luther had learned from Erasmus the importance of the printing press in projecting intellectual influence within society. In 1520, he began to advance the cause of his reformation by appealing directly to the German people, over the heads of clerics and academics, through the medium of print. It was a tactic that would be imitated throughout Europe, as the power of the pamphlet became obvious to all.
Luther now began to have the popular impact that he knew was essential if he was to change the shape of the church, rather than tinker with academic niceties. He would do this by using the vernacular as a means of theological communication.
Why was this development so important? The language of the academy, the church, and the state in western Europe throughout the Middle Ages was Latin. There was an obvious need for a common language to allow communication across this vast and diverse region of the world. Latin was the language of the great Roman poets, rhetoricians, politicians, and philosophers, and of highly influential Christian theologians such as Augustine of Hippo, Ambrose of Milan, and Tertullian.
Luther knew that anything he wrote in Latin would be understood by the educated elite across Europe. Yet Luther wanted to reach beyond an academic readership and touch the hearts and minds of ordinary people. The decision to publish in German was iconic, making a statement about the inclusive nature of the reformation that Luther proposed to pursue. To publish in Latin was to exclude the ordinary people.
From that moment onward, one of the hallmarks of Protestantism would be its use of the vernacular at every level. Most importantly of all, the Bible would also be translated into the language of the people.
An example will illustrate the importance of both printing and the use of the vernacular to the propagation of the ideas of the Reformation. A crucial turning point in the French Reformation was marked by the publication of the French-language edition of Calvin’s Institutes of the Christian Religion in 1541. Suddenly, coherently expressed and carefully justified radical reforming doctrines were available within France in a language which most could understand. There was something approaching panic in official circles in Paris.
On 1 July 1542, the Parisian parliament directed that all works containing heterodox doctrines, especially Calvin’s Institutes, were to be surrendered to the authorities within three days. Calvin’s Institutes were thus seen as the spearhead of a Genevan assault upon the French Catholic church, mediated through the printed word in French. The reaction from the booksellers of Paris was immediate: they protested that they would face financial ruin if they were prohibited from selling such books. It seems that there was a major market for works which were considered to be dangerously unsound by the authorities – further evidence of the importance of a literate and affluent laity in promoting the ideas of the Reformation.
Indeed, Laurent de Normandie, Calvin’s friend and bookseller, found the contraband book trade so profitable that he emigrated to Geneva, in order that he might publish such books rather than just sell them.
McGrath, Alister E., Reformation Thought: An Introduction (pp. 15-16). Wiley. Kindle Edition.