This dissertation focused on the examination of the issue of centrality of repentance, one of the key issues of the noble religion of Islam. The dissertation was divided into an introduction and three chapters. The preface focused on the definition of the term "doctrinal thought" and "Muslim works", and highlighted their relation to the research. Chapter one focused on ontology of the centrality of the repentance and demonstration of Koranic presentation of its concept as well as tracking of their contexts and uses, and their relation to combination between granting of inheritance and punishment. Chapter two discussed about seven key works of old and modern doctrinal though, and tracked their focus on repentance in terms of classification and application. The chapter also compared the centrality of repentance in the Clear Koran and doctrinal thought. Chapter three addressed the same issue in the modern Muslim ideology and works, and presented a proposal in general features in an attempt to reform the deficit of doctrinal though to explore where repentance can be utilized in thought and work. The dissertation drew set of conclusions, among which is that the Clear Koran clearly documented the relation between repentance and the succession and reward in different contexts, and made repentance the central way to paradise. Its concept includes making of reality and reform of sins. Therefore, it is one of the best priorities of Islamic reform. In the doctrinal though classifiers delayed the topic of repentance in treatment of disobedience, and brought other topics before it, such as judgment on the disobedient, or were finally silent about it. The research concluded that authors of only 10 out of 600 books classified repentance in detail and utilized it. This omission of repentance was separated from succession and punishment. Those works forgot sufficient discussi0on of repenting, fulfilling believer, in contrast to the disobeyer whose punishment without repentance was addressed in defining its punishment, even if without repentance. The dissertation indicated that Ibadism, Mu'tazilism and Zaydism are the groups that are most exposed to repentance but all of them show limitation of the works of repentance as compared to its centrality in the Clear Koran. The research showed that modern Muslim was affected by old doctrinal thought. Adjournment that takes reality for granted and omission of repentance as phenomena of contemporary life that tends to exclude religion. The study ended by defining the key positions of focus on repentance in reform, including that its topic shall be listed in the topic of repentance between the two pillars of belief in Allah and the Judgment Day, and the necessity to use it within the doctrinal and intellectual positions in the way that confirms that the repentant got rid of the threat with focus on the pillars of repentance, such as commanding charity and renouncing the abominable, as well as restoration of the system of custody and acquittal, and effectuation of the family system in education ending by focus on the belief of repentance in the various works of Muslim nowadays.