Originally a monk at the
Monastery of Qartmin, Athanasius became Bishop of
Maiperqat, a bishopric subordinate to the
Metropolitan Bishop of
Amid. During his tenure as bishop, Athanasius is known to have used church funds to obtain the support of the Caliph
Marwan II to strengthen his position. By 742/743, Athanasius had been granted the title of Metropolitan of Mesopotamia, potentially due to the simultaneous growth and decline of Maiperqat and Amid respectively, as well as the decrepitude of Severus, Bishop of Amid. As metropolitan, Athanasius granted his student Isaiah of Ashparin administrative control of the greater part of the diocese of Amid as a result of Severus' inability to lead the diocese. During the late 740s, however, this appointment caused Athanasius to come into conflict with the patriarch
Iwannis I who ordained a certain Abay, former Bishop of Arzun, as the new bishop of Amid. This conflict was exacerbated by Iwannis' failure to ordain Dionysius, Athanasius' appointment to the empty see of Tur Abdin, after the death of its former incumbent Athanasius of Nunib. At the Synod of Tella in 752, Athanasius expanded his authority as metropolitan from the area of the former Roman province of
Mesopotamia to the entirety of
Upper Mesopotamia through the use of implicit threats of reprisals from the Muslim authorities, despite the protests of the bishops. Athanasius commemorated his success with the erection of a new cathedral in the city of Maiperqat. He later used his new authority to ordain his student
Iwannis Isaac as Bishop of
Harran and depose the bishops of
Samosata and
Singara. Athanasius also succeeded in having Iwannis Isaac ordained as the patriarch and successor to Iwannis I in 754. Daniel, son of Moses of Tur Abdin, later claimed that Athanasius secured Iwannis' elevation to the patriarchal office by organising the election fraudulently. Athanasius succeeded Iwannis in 756 and served as patriarch until 758. ==References==