Confessor against Iconoclasm
The iconoclast controversy, which divided the Byzantine Church through much of the eighth and ninth centuries, began under Leo III the Isaurian, who moved against the public veneration of icons. Saint John, as bishop of Polybotum, set himself against this policy, denouncing the emperor's heresy and impiety and instructing his people in the Orthodox understanding of the icons. For this steadfastness he is numbered among the confessors of the faith rather than the martyrs, having upheld the truth without, by the record of his life, suffering death for it.
His resistance placed him among the hierarchs of Asia Minor who refused to surrender the icons to imperial command. The memory of such bishops was honored in later generations, after the veneration of icons was restored, as witnesses who had kept the faith through the period of persecution.