Luther and His German Bible
Any discussion of Luther’s doctrine of Scripture, and in this case his promotion and defense of its perspicuity, is not complete without at least mentioning Luther’s arduous work of translating the Bible from the original languages to German. It is no secret that the Catholic Church was vehemently against translations of the Bible in the vernacular. It cost William Tyndale his life and John Wycliffe was hated for his work in translating the Bible into English by the Catholic Church. So too Luther’s translation was unwelcomed by Catholic authorities. Luther wanted nothing more than for his fellow Germans to be able to read the Bible in their own tongue. So long as the Bible was read exclusively in Latin, the Church would never be fully Reformed. The Catholic Church kept its stranglehold on the common men by not allowing them to read the Bible for themselves. If the people could only read the Bible for themselves, Luther’s revolt would be validated and the cause of the Reformation would be complete. Luther believed that once the Bible was made available to the common person, the abuses of the Church would be made evident and Catholicism would crumble.
It took Luther only eleven weeks to translate the New Testament,  and he published it in September 1522 (known as the September Testament). It would not be until 1534 when Luther would finish the Old Testament and first publish the entire Bible. Many have commented on the excellence of Luther’s translation which helped shape modern German. Luther would continue to revise the German Bible until his death.
The Catholic response, predictably, was not positive. Just as the Church opposed Wycliffe and other translators, the Church stood against the translating of the Bible into German. It was standard Catholic teaching that Scripture was not clear and to translate the Bible into the vernacular will only cause more confusion. In 1486, the Archbishop of Mainz had issued an edict
forbidding any unapproved German version in his diocese. He defended his action on the ground that in his office he was required to guard the purity of the divine Word. Those who were trying their hand at turning the Bible into German were the most part incapable of doing justice to their task, he thought. In any case, he added, it is most dangerous to place the Holy Scriptures in the homes of ordinary people, where even women might read, if they could, or at least hear, since they are unable to come to a right judgment about them. [Archbishop] Berhold was giving expression to the general mind of the Church. 
Likewise, Johann Geiler from Kaisersburg, though an advocate for Church reform, was against the translation of the Bible into the vernacular. He argued that
It is a bad thing to print the Bible in German. It must be understood far differently from the way in which the text sounds. It is dangerous to put a knife into the hands of children and let them slice their own bread. They can only wound themselves with it. So also, the Holy Scriptures, which comprise the bread of God, must be read and interpreted b people who have requisite knowledge and experience and who are able to determine the true sense. 
Geiler, here, is echoing the Catholic sentiment of his time. The Church believed that a vernacular Bible in the hands of common people was a dangerous thing. Like most Catholic leaders at this time, Geiler believed that Scripture’s obscurity meant that only trained theologians could read and interpret the Bible for the laity with the Pope standing as the final interpreter.
Notice that the difference between Luther and the Church was not the authority of Scripture, but its clarity. Luther held dearly to its perspicuity and thus translating the Bible to the vernacular was only natural. The Catholic Church, on the other hand, feared that an ignorant people untrained in theology and hermeneutics would come to damnable heresies or at the very least be extremely confused by what they read.
So though on the surface the two sides were debating the merits and necessity of vernacular translations, they were really debating its perspicuity. The belief in Scripture’s clarity drove Luther to translate the text while the rejection of Scripture’s clarity drove the Church to oppose its publication.
 Luther translated at about 1,500 words per day. See James M. Kittelson, Luther the Reformer: The Story of the Man and His Career (Minneapolis: Augsburg Publishing House, 1986), 175.
 Willem Jan Kooiman, Luther and the Bible, trans. John Schmidt (Philadelphia: Muhlenberg Press, 1961), 86-87.
 As quoted in Arthur Skeving Wood, Captive to the Word: Martin Luther – Doctor of Sacred Scripture. Grand Rapids: William B. Eerdmans Publishing Company, 1969.
The Real Divide: Luther, the Reformation, and the Fight Over Perspicuity - Part 1
The Real Divide: Luther, the Reformation, and the Fight Over Perspicuity - Part 2
The Real Divide: Luther, the Reformation, and the Fight Over Perspicuity - Part 3
Theology - Luther: Right Doctrine and Righteous Living Go Hand-in-Hand - A Message the Church Needs to Recover
Reviews - Reviews in Brief: Martin Luther and the Reformation
Reviews - The Theology of the Reformers
Reviews - The Unquenchable Flame
Reviews - Luther: Man Between God and the Devil
Reviews - The Trial of Luther
Reviews - Martin Luther: The Christian Between God and Death
Reviews - "On the Necessity of Reforming the Church" by John Calvin
Reviews - John Calvin: A Heart for Devotion, Doctrine, & Doxology
Reviews - Christianity's Dangerous Idea