List of the Ecumenical Councils

The first ecumenical council was the Council of Nicea in 325 which fixed the format of a prayer (the Nicene Creed) still used in Christian services today. Other rules created at this council include a rule against castration of clergy, and one against having a woman live with a member of the clergy unless she is a close relative or above suspicion, according to All Catholic Church Ecumenical Councils - All the Decrees.
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