Sectarianism, from the beginning of Islam until today, has always been a serious challenge for the unity of the Islamic Ummah, and in the contemporary era, sectarian actions have had destructive effects not only in the religious dimension but also in the political, social and cultural dimensions and have become a central factor for tension in many countries. has become Islamic. Therefore, it is necessary to investigate its nature, types and causes. With the aim of examining these three axes, the main question of this research is: What are the nature, types and causes of new sectarian actions in the contemporary Islamic world, and what similarities and differences do these actions have with historical sectarianism? This research has reached the conclusion that the nature of religious sectarianism in the contemporary Islamic world is different from historical sectarianism by using the method of proof (inference from effect to cause) and discourse analysis. Ancient sectarianism was mainly an internal process in Islamic society that had its own roots and was less influenced by external factors. But contemporary sectarianism is formed as an external program, using the historical and theological lineage of ancient sectarianism and is mostly influenced by external factors. As a result, contemporary sectarianism is more of a program than a process, and historical Muslim sectarianism has turned into contemporary religious sectarianism under the management and planning of opponents of Islamic unity and civilization.