The monk Martin Luther just wanted to discuss the problems he saw in the Catholic Church. But what happened in Wittenberg on October 31, 1517 would forever change Germany, Europe, and the rest of the Christian world. To understand the tremor that Luther unleashed with his 95 theses, we have to go back to the era he lived in.

In the late Middle Ages and beginning of the modern era, the Christian faith was dominated by the Roman-Catholic Church. The Church's dogma and rules dictated people's lives, and God was seen as a judgmental figure who never let a mistake go unpunished.

Events that couldn't be explained - like personal tragedies, bad harvests or even wars - were viewed as the consequences of a pact with the devil. Those thought to have entered into such deals were usually burned at the stake.

Martin Luther's bolt of lightening

Luther's birth house in Eisleben

Martin Luther was born in Eisleben in 1483 as the son of a miner. In 1501, he began his studies at the University of Erfurt. Four years later, he completed his Masters degree and then began studying law.

Then something life-changing happened to Luther. In July 1505, he was caught in a big storm and was struck by lightening. Faced with the prospect of death, he feared having to face God unprepared, so he called to Saint Anna, the patron saint of miners, and pledged to become a monk.

Less than a fortnight later, Luther knocked on the door of the Augustinian cloister in Erfurt and asked to be accepted into the order.

Luther's early life as a monk

Driven by his search for a merciful God and fear of missing out on life after death, Luther saw an opportunity to experience a fulfilled life inside the walls of the monastery.

A Bible from the 15th century

From the beginning, the young monk was conspicuously obedient. He prayed for six hours a day and fasted; he practiced self-reflection, mortification and confession. Later, Luther would say about his life in the cloister, "If ever anyone has ever managed to get into heaven by being a monk, I wanted to do that too."

Less than two years after entering the monastery, Luther became a priest in 1507. Theological teaching was at the center of his studies, which he threw himself into with zeal.

First experience with the selling of indulgences

In 1510, Luther was sent to Rome on business by his Augustine order. The trip would prove pivotal. The Curia was struggling financially due to the expensive construction of St. Peter's Basilica. To raise money, the church leaders introduced the selling of indulgences. The congregation was told they could attain the forgiveness of sins by committing good deeds - or paying the Church. Prices were set according to income, and even those who'd already died could allegedly be rescued from the fires of hell if their relatives coughed up a few coins.

It wouldn't be until much later that Luther would take a critical view on the practice he had witnessed.

Luther's search for acceptance by God

Lucas Cranach, the Elder painted Martin Luther in around 1520

In 1512, Luther - already highly respected by his colleagues and superiors - earned his doctorate in theology and became a professor at the University of Wittenberg.

Nevertheless, Martin Luther was still searching for a merciful God and continued to ask the question: What must I do to be approved by God? None of the Church's rituals or rules was able to answer this question.

Luther continued fervently to read the Bible and was particularly moved by the Apostle Paul's letter to the early Roman church, where he read about justification by the blood of Jesus Christ.

The theologian gradually understood what would become the core of the Reformation: God is not just a just judge, but also a father who loves the people he created and who sent his son to pay the price for the sin that was separating them from him.

As Luther discovered in the Bible, anyone who believes in God and his son Jesus Christ is given the free gift of justification before the Almighty. The monk had finally found the answer to his question.

Luther's four pillars of faith

Through his study of the Bible, Martin Luther developed four key theological pillars. The first is the Holy Scripture. He saw the Bible as the only benchmark of truth, while the Church at the time also relied on additional texts written by the pope and the synod.

Now, All Saints' Church in Wittenberg is a popular tourist attraction

Secondly, salvation only comes through God's grace and not by good works. This belief made the selling of indulgences obsolete.

Thirdly, Luther concluded that Jesus Christ, through his death on the cross, which paid the penalty for all sin, is the only bridge between humanity and God.

Finally, we are saved by faith alone, believed Luther.

"Christian life is entirely based on faith," he said. "By faith, Christ lives in us and is one with us. By faith in Christ, Christ's righteousness becomes our righteousness and what is his, becomes ours."

These beliefs revolutionized the relationship between humans and God. Realizing they were made accepting to God by his grace and their faith alone, people could approach him directly without the help of an intermediary priest.

Consequentially, the Church lost its power with Luther's teachings and its hierarchies began to crumble. While his work is indeed revolutionary, Luther himself believed he was simply reinstating old, forgotten principles rather than expressing new and unwelcome beliefs.

Painted by Lucas Cranach, the Elder, in 1520, this is one of some 500 pictures of Martin Luther that were painted during his lifetime

As a theology professor, Luther taught his theological viewpoint to his students and preached on it during mass. At first, he went unnoticed. But Luther was determined to correct the Church's unbiblical theology and initiate a return to the origin of the Christian faith. Most of all, he wanted to put an end to the selling of indulgences, which had become a common practice in Germany.

Luther's famous 95 theses

In October 1517, Luther planned a debate about the practice of selling indulgences. No one came, so he sent his theses directly to Cardinal Albert of Brandenburg, Elector and Archbishop of Mainz. At the same time, he is said to have nailed these 95 theses to the gate of the All Saints' Church in Wittenberg, which served as a kind of billboard at that time.

The move unleashed a debate that shook that foundation of the Church. With the help of the still relatively new printing press, Martin Luther was able to spread his message quickly.

October 31, 2017 will mark the 500th anniversary of Luther's world-changing act, and exhibitions and events will be held over the next year to mark the event that sparked the Reformation, and the birth of Protestantism.