Final answer:
The great controversy that divided the Byzantine Empire during the eighth and ninth centuries was whether or not Christians could use images in worship.
Step-by-step explanation:
The great controversy that divided the Byzantine Empire during the eighth and ninth centuries was whether or not Christians could use images in worship. This conflict is known as the Iconoclastic Controversy. One side argued that the use of religious icons was idolatrous, while the other side believed that icons were essential for understanding and practicing the Christian faith.
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