Moscow Sobor of 1666–1667
The Moscow Sobor of 1666–1667 was a council of the Church of Russia, with representation from other patriarchates, convened in Moscow, Russia by Tsar Alexis of Russia. The business of the council was concerned mainly with Russian liturgical practices that were inconsistent with those of the Orthodox Churches on the eastern Mediterranean world.
The Sobor was convened in 1666 in Moscow during the reign of Tsar Alexis by Metropolitan Pitirim of Krutitsy, locum tenens after the retirement of Patriarch Nikon to a monastery after a dispute with Tsar Alexis. In addition to the Tsar, Joasaph (Novotorzhets) who became patriarch during the sobor, and Russian clergy, those attending the sobor included Patriarch Macarius of Antioch, Metropolitans Athanasius of Iconium (representing the Ecumenical Patriarch) and Ananias of Sinai (representing the Patriarch of Jerusalem), and Patriarch Paisius of Alexandria who presided.
The council officially established the reforms that had been brought forward during the patriarchate of Patr. Nikon and anathematized all those who opposed the changes to the old Russian books and rites made to comply with the Church's liturgical unity. Even the old Russian books and rites themselves were anathematized. Old Ritualists were condemned for refusing to comply with such liturgical changes as celebrating feast days on the same day as the rest of the Orthodox Churches, making the sign of the cross with three fingers instead of two, and not kneeling on Sundays.
One of the decisions during the sober was a specific ban on a number of depictions of God the Father and the Holy Spirit, which then resulted in a whole range of other icons being placed on the forbidden list.
Also, the sober forbad the iconographic depiction of the Holy Trinity with God the Father as an old man and the Holy Spirit as a dove, because it transgressed the rules of Orthodox iconography as expressed by the Seventh Ecumenical Council, and because the form of this image is of unorthodox Western origin.