Complex sentence: He was born in Constantinople of a strictly orthodox family, which had suffered from the earlier iconoclasm, he nevertheless entered the service of the State, became cabinet secretary, and under Irene took part in the synod of 787 as imperial commissioner.
Split into simpler sentences: He was born in Constantinople of a strictly orthodox family, which had suffered from the earlier iconoclasm. Nevertheless he entered the service of the Empire, became cabinet secretary, and under Irene took part in the synod of 787 as imperial commissioner.