The Ethiopian Orthodox Täwahdo Church (hereafter EOTC) witnessed the most destructive dogmatic controversy by the dawn of the 17th century. The manipulation of the issue by the royal court and the clergy for power and privileges let the crisis continue for more than two and half a century. The feud not only threatened the unity of the church, but also considerably contributed for the ultimate decay of the Ethiopian state during the Zämänä Mäsafent. The impact of the schism was apparent when it took the concern of state builders of the 19th century. In spite of its enormous contribution in the disintegration and re-unification of the country, the controversy is a theme of Ethiopian history which attracted little attention. The scholarly works dealt on the issue are heavily shaped by either the outer contexts of the sectarian literature or the changes of the 19th century. The essences of qesäța and sarcastic portrayals of traditions and the sects’ intensive edition, deletion and modification of library works are unnoticed. This complicated the study of the origin and root of the controversy as well as the dogmas defended by each sect. Hence, this dissertation gives emphasis to fill the major historiographical gaps characterizing the scholarly literature. A considerable attempt has been made to show the dynamics of the controversy by treating each major development on its own time perspective. This dissertation is built mainly on sectarian treatises, hagiographical traditions, and royal chronicles. Enormous attempt has also been made to review the secondary literature and extract relevant information on the issue. Intensive interview was made with church scholars versed in commentaries of the scripture to properly understand the theological contexts of the tenets of the sects. An integrated thematic and chronological approach of analysis is applied to better reconstruct this very intricate dogmatic feud. A careful look into primary sources indicates that the main source of the schism was the Catholic Church’s long endeavor to detach the EOTC from Alexandria and submit to its See of Rome. The lasting impact was the split of the EOTC clergy along dogmatic lines in the early 17th century. Therefore, this dissertation argues that the EOTC had well defined Trinitarian and Christological dogmas prior to the advent of Jesuits which was defended by the Täwahdo party throughout the course of the controversy. The clergy disagreed on further interpretation of the held miaphysite dogmas of the EOTC. The work gives a new perspective into the nature of the sectarian literature as well as scholarly view and thus it will serve as important reference for further research works