Episcopate and the Seventh Ecumenical Council
Euthymius was ordained metropolitan bishop of Sardis, a major see in western Asia Minor, by Patriarch Tarasios of Constantinople in the period between about 784 and 787. His elevation fell during the brief peace in which the empress Irene and Tarasios worked to reverse the first phase of Byzantine Iconoclasm.
In 787 he attended the Second Council of Nicaea, recognized as the Seventh Ecumenical Council, which formally condemned Iconoclasm and affirmed the veneration of holy images. According to the accounts that survive, Euthymius played a leading part in the council's proceedings and advocated for the restoration of traditional icon veneration and the reinstatement of bishops who had been exiled under the iconoclast emperors.