Why was the struggle of the iconoclasts in Byzantium for a long time successful, but they never won the final victory?

In the 8th-9th centuries Byzantium was a military monarchy: the army constantly repelled the raids of Muslims and Bulgarians, which strengthened the authority of the emperors. But the struggle of the same emperors with the monks – admirers of icons – did not find support in the Romans and ended in failure as soon as the external danger passed. The fight against icons in the 8th century turned out to be a fight against monasticism and its final victory.

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