Martin Luther was born at Eisleben, Germany. He entered the Augustinian order of the Roman Church in 1505 (age 21), and three years later he was sent to teach at the University of Wittenberg. He became a priest and celebrated his first mass at age 23. Then followed a trip to Rome, and many other advancements, but nothing brought peace to his soul. However, at age 29, while working out a personal anxiety, Luther in his studies of the Bible, became aware that God justifies a man through faith in the finished work of Christ alone. In 1517 he nailed his 95 theses against the practice of indulgences to the castle church doors. The intense reaction of the Roman Church authorities led to Luther's excommunication in 1521. Thus began the Protestant Reformation. Luther married a former nun, Katrina Von Bora, in 1525, and she became his true helpmeet in the great work before him. Germans are indebted to him for translating and publishing the Bible in "low" German, the language of the common people. He also gave us many hymns, notably "A Mighty Fortress is Our God " (1529).