This book is the third volume of the Comparative Tafsir Research series, which consists of five chapters: Chapter I is on generalities and encompasses topics such as "reflection on the theory of the Promised Savior in different religions and nations", "a short review of the previous studies on Mahdi'ism in Islam,", "classification of verses about Mahdi'ism and revision of this issue". The second chapter deals with a comparative study of the "declaration of the true religion" verses (al-Tawba/33-32), and the third chapter comparatively examines the Tafsir of the verse "promise" (al-Nur/55). After presenting preliminary discussions, each of these two chapters in three sections examine and evaluate Shia and Sunni’s views. The fourth chapter in two sections contains "an explanation of the true religion" and "the features of the religious dominance age" in order to solve some controversies over the meaning of the true religion, and to reveal all features of the epoch of appearance on the continuum of "oneness of God and monotheistic life". The fifth chapter takes a step in introducing Imam Mahdi (AS) and, according to the common points of Shia and Sunni’s views in these verses, partially reaches knowledge about Imam Mahdi (AS) through studying the mission of Imam Mahdi (AS) in restoring religion and analyzing his characteristics in Shia and Sunni’s teachings