"In the little town of Wittenberg, Germany, on this day, October 31, 1517, a priest nailed a challenge to debate on the church door. No one may have noticed then, but within the week, copies of his theses would be discussed throughout the surrounding regions; and within a decade, Europe itself was shaken by his simple act. Later generations would mark Martin Luther's nailing of the 95 theses on the church door as the beginning of the Protestant Reformation...
In 1505, Luther entered the Augustinian monastery, and in 1507 became a priest. His monastic leaders sent him to Rome in 1510, but Luther was disenchanted with the ritualism and dead faith he found in the papal city. There was nothing in Rome to mend his despairing spirit or settle his restless soul. He seemed so cut off from God, and nowhere could he find a cure for his malady.
Martin Luther was bright, and his superiors soon had him teaching theology in the university. In 1515, he began teaching Paul's epistle to the Romans. Slowly, Paul's words in Romans began to break through the gloom of Luther's soul.
The more Luther's eyes were opened by his study of Romans, the more he saw the corruption of the church in his day. The glorious truth of justification by faith alone had become buried under a mound of greed, corruption, and false teaching. Most galling was the practice of indulgences -- the certificates the church provided, for a fee, supposedly to shorten one's stay in Purgatory. The pope was encouraging the sale of indulgences. He planned to use the money to help pay for the building of St. Peter's Basilica in Rome."
Luther Posted 95 Theses - 1501-1600 Church History Timeline
Although Halloween has been linked historically to ancient pagan observances and whitewashed by the religious establishment in the Middle Ages, there is some redemptive history associated with this particular day in the credence and actions of Martin Luther.