Abstract :

The First Council of Nicaea (325 CE) represents a pivotal moment in early Christian history, establishing theological doctrines that would shape the future of Christianity. This paper examines the concept of cognitive dissonance in the context of the Nicene Council, exploring how internal conflicts between established theological beliefs and the new doctrines being introduced may have influenced the decisions and behavior of key participants. By applying Leon Festinger’s theory of cognitive dissonance to historical religious decision-making, the study posits that the council's theological disputes, particularly regarding the nature of Christ and the relationship between the Father and the Son, reflect underlying psychological tensions. These tensions likely arose as bishops and theologians were faced with reconciling their previous theological understandings with the emerging Nicene Creed.  This research use a phenomenology method to know human perception about Christ and relationship between the Father and the Son. The research also discusses how the imposition of orthodox positions during the council, under the threat of excommunication or political pressure, may have contributed to the reduction of cognitive dissonance, resulting in public conformity while underlying disagreements persisted. This analysis highlights the intersection between psychology and religious history, providing a deeper understanding of the cognitive processes involved in the formulation and acceptance of doctrinal changes in early Christianity.