According to some historians and scholars, the early Christian Church was very loosely organized, resulting in diverse interpretations of Christian beliefs.[32] In part to ensure a greater consistency in their teachings, by the end of the 2nd century Christian communities had evolved a more structured hierarchy, with a central bishop having authority over the clergy in his city,[33] leading to the development of the Metropolitan bishop. The organization of the Church began to mimic that of the Empire; bishops in politically important cities exerted greater authority over bishops in nearby cities.[34] The churches in Antioch, Alexandria, and Rome held the highest positions.[35] Beginning in the 2nd century, bishops often congregated in regional synods to resolve doctrinal and policy issues.[36] Duffy claims that by the 3rd century, the bishop of Rome began to act as a court of appeals for problems that other bishops could not resolve.[6]