Two councils of the Christian Church, which took place in the city of Nicaea (now Iznik, Turkey). The first Council (325) was summoned by the Roman emperor Constantine and issued a statement of orthodoxy against Arianism (the belief that Jesus Christ was not divine, but merely an exceptional human being), later known as the “Nicene Creed”. The Second Council (787) was called by the Byzantine empress Irene to end the Iconoclastic controversy.