GIOVANNI I. — Chaldean Patriarch from 1681 to 1696. He was first a Nestorian bishop of Diyarbakir (Amida), whose clergy in 1696 had passed from the Catholic Chaldean patriarch to the Nestorian one. In 1672 G. was converted to Catholicism by Capuchin missionaries and in 1675 went to Rome, where he remained until 1677.
In order to maintain himself against the Nestorian patriarch, upon whom he depended according to civil law, he needed the title of patriarch, which was in fact granted to him by the Turkish government. Meanwhile, since the Catholic Chaldean patriarch Simeon XIII had reverted to Nestorianism, the Holy See conferred upon G. on 8 January 1681 the title of patriarch (though not of Babylon). Owing to his frail health, weakened by tribulations and persecutions, G. retired to Rome and tendered his resignation. The Holy See appointed on 18 June 1696 as his successor Giuseppe Sibilà. G. died in 1707.