Uzroci protestantske reformacije podijeljeni su u pet skupina: povijesni, teološki, duhovno-religiozni, politički, socijalni i psihološki i teologija Martina Luthera. Do dvadesetoga stoljeća provlačila se tradicionalna teza da glavni uzrok reformacije trebamo tražiti u brojnim zloupotrebama u Crkvi. Danas i katolički i protestantski autori promatraju problem mnogo šire i dublje te zahvaćaju teološku misao, osobito nominalizam koji je bitno utjecao na samoga Luthera. U spletu različitih okolnosti – političkih, socijalnih, psiholoških – dominirala je i Lutherova osobnost. Kao profesor biblijskih predmeta osobito se bavio proučavanjem poslanica Rimljanima i Galaćanima. Pitanje oprosta pokrenulo je veliku lavinu koja se nije dala zaustaviti. Oprosti su samo povod, ali ne i uzrok protestantskoj reformaciji.; The causes of the Protestant Reformation are divided into five groups: historical, theological, spiritual-religious, political, social and psychological, and the theology of Martin Luther. Until the twentieth century, the traditional opinion was that the root cause of the Reformation should be sought in the many abuses in the Church. Today, both Catholic and Protestant authors look at the problem much broader and deeper and embrace the theological thought, especially the nominalism which significantly influenced Luther himself. In a combination of different circumstances – political, social, psychological – Luther’s personality also dominated. As a professor of Bible courses, he was particularly interested in the study of the Epistles to the Romans and Galatians. The question of indulgences triggered a large flood that could not be stopped. Indulgences were only the last straw but not the cause of the Protestant Reformation.