(Behr, 104-107; 263-267), Ayres (222-229)
Basil emerges in the second half of the 4th century as, probably, the key player. His theological contribution, coupled with politico-ecclesiastical manoeuvres, help to both develop, and effect the triumph of, pro-Nicene theology. b. ca. 330, into aristocratic Christian family. Studied in Athens, taught rhetoric in Caesarea; toured ascetic settlements in Asia Minor, Syris, Palestine, and Egypt.
Although the earliest of Basil's significant works, Contra Eunomius, appears in 364, his most significant contributions lie in the 370s. June 370 he is elected as successor to Caesarea, and in 372 confronts and wins over Valens (at least to personal favour): he is entrusted with oversight of Armenia even as Cappadocia is split into two. The split of Cappadocia is the catalyst for Basil to appoint a number of new bishops to new sees in response, not least the Gregories.
Two constant problems beset Basil's alliance-building program. Firstly, Valens and the government were anti the pro-Nicenes, so it was difficult “to act openly against the Homoians” (Ayres, p222). Secondly, unpredictable personal antipathies and ambitions made alliances, even among those who were doctrinally close, difficult to achieve and maintain.
He sided with Meletius in Antioch, sought rapprochement (with ongoing difficulties) with Damasus of Rome (who continued to support Paulinus in Antioch); ultimately his overtures to Rome failed due to continuing suspicion, but the Tome of Damasus reveals their growing theological agreement, even if Basil died before it was finally reached. In the late 370s he is writing about and against Pneumatomachians and Apollinarius, with De Spiritu Sancto ca.375. He died January 1, 379, shortly before the accession of Theodosius, but having laid the foundation for pro-Nicene theology to triumph at Constantinople 381.
Part II: Basil's Theological contribution
Part III: De Spiritu Sancto, and selected Letters