Final answer:
Constantine I repealed the Edict of Milan and promoted religious tolerance to make Christianity a unifying force in the Byzantine Empire.
Step-by-step explanation:
Constantine I played a significant role in making Christianity a unifying force in the Byzantine Empire. He repealed the Edict of Milan, which had previously allowed religious freedom to Christians. By doing so, he established Christianity as the favored religion of the empire, encouraging its spread and growth. This unifying force was further strengthened by Constantine's promotion of religious tolerance, as he allowed Christians to practice their faith openly without persecution.
Learn more about Constantine I's impact on Christianity in the Byzantine Empire