He is referred to by St Ambrose as "Mercurinus", but in an extravagant document written at the height of a bitter dispute with the Imperial court, apparently in order to accuse his rival with having changed his name from Mercurinus in order to curry favour with supporters of another Auxentius who had been Ambrose's predecessor; the robustness of this accusation is unknown.
[1] In Milan, seat of the Western Imperial court, Nicene and Arian controversy flared high.
[2] He wrote an account of the life and death of Ulfilas that the Arian bishop Maximinus included (383) in a work directed against St. Ambrose and the Synod of Aquileia, 381.
This favourite of Empress Justina was the anti-bishop set up in Milan by the Arians on the occasion of the election of Ambrose.
The Letter of Auxentius (ca 400) was preserved in the margins of a manuscript of De fide of Ambrose.