John of Constantinople, also known as John the Confessor, was an abbot of the Cathares Monastery, in Constantinople. He clashed with the Byzantine Emperor Leo the Armenian, who was instituting a policy of iconoclasm. John survived torture for his iconodulism. He is considered a saint by the Eastern Orthodox Church and the Roman Catholic Church, and is celebrated by them on 27 April and 18 April respectively.

April 18

Canonized

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18