Abstarct: Numerous factors such as geography, weather, climate, beliefs, knowledge, customs, social values, ethics, arts, and social rituals influence the design of places of worship. This study examines climatic and religious components among Muslim and Christian communities to determine which factor—climate or religious/ritual beliefs—plays a more significant role in shaping the architecture of mosques and churches. To this end, two case studies from the historic fabric of Isfahan were selected: the Shah Abbas (Imam) Mosque in Naqsh-e Jahan Square and the Bethlehem Church in the New Jolfa district. Both structures date belongs to the Safavid era, represent masterpieces of that period, and are situated in close proximity within the same climatic zone. Initially, a descxriptive-analytical study regarding climatic factors was conducted through literature review and direct site observation. Subsequently, to assess the religious influence on architectural form, the Delphi method and expert consultations were employed to analyze religious beliefs. The findings indicate that climate is the primary factor organizing the form and spatial structure of the Shah (Imam) Mosque, while Muslim religious beliefs serve to enrich its meaning and aesthetic principles. In contrast, regarding the Bethlehem Church, climate plays a moderating role, whereas Christian religious and ritual beliefs dominate the church's floor plan and overall architectural structure.