→Ante-Nicene era (100-325): 270
*265 The word "[[Homoousios]]", "of the same substance", to define relationship between [[God the Father|Father]] and Son, used for first time by Modalist Monarchians of Cyrene, playing an important part in defining Orthodoxy at [[First Ecumenical Council|Nicene Council]] in 325.
*274-275 [[w:Persecution_of_early_Christians_in_the_Roman_Empire#Persecution_under_Aurelian|Persecution under Emperor Aurelian]].
*270 Death of [[Gregory the Wonderworker|Gregory Thaumaturgus]]; [[w:Porphyry of Tyre|Porphyry of Tyre]] writes ''Against the Christians'', a powerful anti-Christian book, causing several Christian contemporaries to try and refute him, and which was later banned and burned in 448; first priest ordained in [[w:Al-Mada'in|Seleucia-Ctesiphon]].
*272 Martyrdom of Sabbas Stratelates ("the General") of Rome and 70 soldiers.
*284 [[Diocletian]] becomes Roman emperor, persecutes Church and martyrs an estimated one million Christians; martyrdom of [[Cosmas and Damian (Rome)|Cosmas and Damian]], Andrew Stratelates ("the General") and 2,593 soldiers with him in Cilicia; the ''Era of the Martyrs'' dating system, currently used by the Coptic Church, had its beginning on this date, its year one.