Preface: This article was written in collaboration with ChatGPT.

Protestantism is a broad category of Christian traditions that emerged during the European Reformation of the sixteenth century. It is not a single church or a unified denomination, but rather a collection of reform movements. What these movements share is not a perfectly consistent body of doctrine, but a systematic rejection of the authority structure of the Roman Catholic Church. Protestantism denies that the pope possesses supreme religious authority, maintains that Scripture—rather than church tradition—is the ultimate standard of faith, and holds that salvation depends on faith itself, not on mediation by the church, the sacraments, or good works. At the same time, Protestantism emphasizes that believers can relate directly to God, and that individual conscience occupies a position in matters of faith that cannot be fully replaced by ecclesiastical authority.

The generally accepted starting point of Protestantism is the year 1517. In that year, the German theologian Martin Luther published the Ninety-Five Theses in Wittenberg, publicly questioning the legitimacy of the Roman Church’s sale of indulgences. This act was not, in itself, a political revolution, but a theological and academic challenge. Its historical significance lies in the fact that it explicitly placed individual conscience and the authority of Scripture above the authority of the Church for the first time, fundamentally destabilizing the power structure of the medieval Latin Christian world.

That 1517 became the starting point of Protestantism was no accident. Long before this moment, Europe had accumulated widespread dissatisfaction with the Church’s financial privileges, judicial privileges, and moral corruption. The spread of the printing press weakened the Church’s monopoly over knowledge and texts; emerging state powers continued to strengthen; and individual religious consciousness was gradually awakening. Luther’s action triggered a chain reaction precisely because it articulated these long-standing structural tensions in theological form and allowed them to spread rapidly through new technologies of communication.

It is important to note that Protestantism was never a unified church system from the outset. The Reformation took different paths in different regions. In the German lands and Northern Europe, a Lutheran tradition centered on Luther took shape; in Switzerland and the French-speaking regions, a Reformed tradition associated with Calvin developed; in England, the Church of England was established under state leadership. These traditions differed markedly in church organization, liturgy, and political relationships, yet they are collectively called Protestant because they all rejected the Roman pope as the highest religious authority.

At its core, the dividing line between Protestantism and Catholicism does not concern belief in God, but the ultimate source of authority. Catholicism insists on the central role of church tradition and papal authority in matters of faith, whereas Protestantism returns ultimate authority to Scripture, to be understood and practiced through individual conscience. This transfer of authority not only transformed Europe’s religious landscape, but also profoundly influenced the formation of modern states, legal systems, and concepts of individual responsibility.

In summary, the starting point of Protestantism was the public challenge to church authority in 1517, and its essence lies in reclaiming the final authority over faith from the Roman Church and relocating it in Scripture and individual conscience.

Martin Luther was born in 1483 in the German lands. He was a Catholic monk rigorously trained in scholastic theology and a professor of theology at the University of Wittenberg. He belonged to the Augustinian order and was fully embedded within the Latin Christian system, not a marginal figure or a political rebel. Luther spent years teaching Scripture, especially texts such as Romans and Galatians. His ideas did not arise from popular anti-church sentiment, but from systematic theological study.

Luther’s personal temperament is essential to understanding him. He was not a relaxed reformer, but a man deeply tormented by the question of how a human being can be saved before God. He was acutely sensitive to his own sense of sin and could not achieve inner certainty through the paths to salvation offered by the Church. Out of this intense, internalized religious anxiety, he gradually developed the theological judgments that would later be seen as subversive.

In 1517, Luther published the text later known as the Ninety-Five Theses. This was not a revolutionary manifesto, but a set of theological propositions written in Latin for academic debate, originally addressed to the university and ecclesiastical scholarly community. Its immediate subject was very specific: the system of indulgences that was being widely promoted in the German territories at the time.

Indulgences allowed believers to reduce the time of punishment in purgatory for themselves or deceased relatives through monetary payment. In practice, the system rapidly became commercialized and was even promoted with slogans such as “When the coin in the coffer rings, the soul from purgatory springs.” Luther repeatedly emphasized that true repentance is an inner turning, not a transaction that can be completed with money. He argued that the Church had no authority to institutionalize forgiveness as an economic act, nor to guarantee spiritual outcomes to believers.

In the Ninety-Five Theses, Luther did not directly deny the existence of the pope, but he made it clear that even if the pope possessed the authority to proclaim forgiveness, he could only declare what God had already forgiven, not manufacture forgiveness through his own authority. This argument appears moderate, but it is logically devastating, because it denies the Church’s active control over salvation.

On the surface, the text opposed the abuse of indulgences; at a deeper level, it addressed a fundamental question: does the Church monopolize the mediating role between human beings and God? If salvation depends on faith itself rather than church institutions, then church authority is no longer irreplaceable. If individuals can understand faith directly through Scripture, then the hierarchical structure of the clergy loses its theological foundation.

Luther’s immediate motivation for publishing the Ninety-Five Theses was not political rebellion, but a conflict between conscience and theology. He believed that the indulgence system not only misled believers but also created a false sense of security, encouraging people to think they could escape genuine repentance through money. The core conviction driving his action was a conclusion he had reached through long study: human beings are saved not by deeds or merit, but by faith alone. This idea later came to be summarized as “justification by faith.”

At the same time, historical conditions magnified the impact of Luther’s actions. The spread of the printing press allowed his texts to circulate rapidly, and German princes’ long-standing resentment of Roman financial extraction made political authorities willing to shelter religious dissent. What Luther had imagined as an internal academic discussion quickly escalated into a public and irreversible confrontation.

In 1517, Luther did not believe he was founding a new religious tradition. His initial hope was for reform within the Church, and he consistently regarded himself as loyal to the core of Christian faith. It was the Roman Church’s trials, condemnations, and eventual designation of him as a heretic that gradually pushed him outside the institutional framework. In this process, Luther moved from being a reformer to becoming the starting point of a historical rupture. In retrospect, Martin Luther was not a man intent on destroying religion, but a theologian who refused to accept the substitution of faith with institutions and money. What he challenged was not merely indulgences, but whether the Church possessed final authority over the meaning of salvation. Once this question was publicly posed, the history of Protestantism had, in effect, already begun.