Luther and the Bible in the Common Tongue

One of the things that was important to the Reformers (as it was to the early church) was that the Word of God be available to people in a language they could understand. This is famously seen in the translational works of Wycliffe and Tyndale, but also in the work of Luther:

Luther began his translation of the New Testament during his enforced exile at the Wartburg, and his work of translating and revising came to occupy him until the end of his life. Amazing as it seems, he apparently completed the first draft of his translation of the New Testament in some eleven weeks, using as his working tools the Greek and Latin editions of Erasmus. Not only did Luther prepare a superb translation, a version that seemed fresh and alive because, as one scholar has phrased it, "he read Holy Writ 'as though it had been written yesterday.'"[FN54] but also, in the process of translation, he helped to sculpt the German language. The development of Neuhochdeutsch, early modern high German, was underway before the appearance of Luther's Bible, due partly to the influence of Saxon Kanzeleideutsch or chancellory German. [FN55] Luther's Bible brought new high German into the parish schools and pulpits and made it the common language for the German people, even though the common folk long clung to their individual dialects. In brief, the language of Luther's Bible "became the language of the people, the langugage used in the studies of the scholars, and the language spoken in the huts of the unlearned."[FN56]

Marilyn J. Harran, Luther and learning: the Wittenberg University Luther Symposium, p. 40.

For several hundred years after the height of Middle High German literature, there was no longer any standard literary language. By far the most important influence on the development of the Modern High German standard language was Martin Luther's translation of the Bible, the first edition of which appeared in 1522 (Old Testament) and 1534 (New Testament). Luther's translation was the first to be written in a direct and uncomplicated - at times even colloquial - style that strove not only to include expressions that were modern and up-and-coming, but also to incorporate linguistic features from as many regions as possible. Its impact on literary German was immense; its core was Luther's native dialect of Thuringian.

Benjamin W. Fortson, Indo-European Language and Culture: An Introduction, 15.78 (p. 367)