Final answer:
Paul taught the Philippian believers that their identity was defined by their 'citizenship in heaven', contrasting the Roman emphasis on social hierarchy and legal status.
Step-by-step explanation:
Paul taught the Philippian believers that they were no longer defined by their Roman citizenship but were now defined by their citizenship in heaven, the new Jerusalem above. The Apostle Paul, influenced by early Christian philosophy, presented a vision that was contrary to the Roman emphasis on social hierarchy and legal status. The early Christian message of universalism and spiritual equality went against the Roman ideals, hence providing a new identity for believers that transcended the traditional Roman socio-political divisions. Christianity's doctrine was inclusive, making no distinctions based on social rank, and emphasizing the spiritual unity and equality of all believers.