He was a strong opponent of Arianism, but was accused of adopting the opposite extreme of modified Sabellianism.
He was condemned by a council of his enemies and expelled from his see, though he was able to return there to live quietly with a small congregation in the last years of his life.
A few years after the Council of Nicaea (in 325) Marcellus wrote a book against Asterius the Sophist, a prominent figure in the party which supported Arius.
[2] Marcellus was deposed at Constantinople in 336 at a council under the presidency of Eusebius of Nicomedia, the Arian, and Basil of Ancyra appointed to his see.
J. W. Hanson (1899) and other Universalist Church of America historians read that Marcellus's theology included a belief in universalism, that all people would eventually be saved.
In his Ecclesiastical History, Sozomen noted that Marcellus, in order to convert the pagans more easily in Apamea, “destroyed the temples of the city and its villages" [6]