Luther the Monk
Luther was an excellent monk, or at least a most devoted one. He was deeply troubled by a pervasive sense of religious guilt; he felt the weight of his own sins painfully and sincerely wished to find some way to be cleansed. The rigors of monasticism seemed to offer what he sought.
He out-did all the other monks in devotion and study. He put himself through every rigor and test, including frequent fasting, long prayer vigils, and self-flagellation. He went to confession constantly, to the point where his confessor warned him that excessive confession was itself a sin of pride.
But for all the vigils and fasts and penances, he never really believed that he was saved, even after he was ordained. All the outward rituals of the Church assured him that he was a good Christian, yet when he looked within his heart he saw nothing that was worthy of God's mercy. And the terrors of Hell were quite real to Luther.
Partly as a result of his scholarship, and partly to put his great energies to work, his abbot assigned Luther in 1508 to the faculty of Wittenberg University. This was a new university, founded by the Elector of Saxony, and it was in need of teachers.
Luther entered ever deeper into his study of Scriptures. His erudition won him respect from his peers, and his occasional sermons were well received, but still in his heart he was troubled. How could he know that he was saved? The question tormented him, despite all the reassurances of the Church. And the Bible was if anything even more troubling, with its many details of what it meant not to be saved.