Part I. The emergence of Christian theology (ca. 150-300). Ptolemy, Letter to Flora -- The Gospel of truth -- Irenaeus of Lyons, Against heresies 1.22.I-22.2, 2.28.I-2.28.9 and 4.20.1-4.20.8 -- Tertullian, Against Marcion I.2-I.5 and 1.22-I.27 -- Hippolytus, Against Noetus 1-11 and 14-17 -- Origen of Alexandria, On first principles, Preface and I.1-I.3 -- Part II. Creeds and controversies (300-400). Arius, Letters to Eusebius of Nicomedia and Alexander of Alexandria -- Creed of the Council of Nicaea (325) -- Eusebius of Caesarea, On ecclesiastical theology 2.1-2.7 -- Hilary of Poitiers, On the Trinity 8.19-8.26 and 8.41 -- Basil of Ancyra, The Synodal letter of the Council of Ancyra -- Athanasius of Alexandria, On the Synods at Ariminum and Seleucia -- Ephrem, Hymns on the faith 40, 73-75 -- Ephrem, Commentary on the Gospel I.2-I.8 -- Basil of Caesarea, Letters 159 and 236.6 -- Ambrose of Milan, On the faith 1 -- Creed of the Council of Constantinople (381) -- Gregory of Nyssa, On the Holy Spirit against the Macedonian spirit-fighters -- Gregory of Nazianzus, Poems 1.1.1-1.1.3 -- Eunomius of Cyzicus, the Confession of faith -- Part III. Doctrinal inheritance and philosophical exploration (400-ca. 570). Augustine of Hippo, Sermon 52 -- Cyril of Alexandria, Five tomes against Nestorius 4.1-4.2 -- Pseudo-Dionysius, On the mystical theology to Timothy -- Boethius, On the Holy Trinity -- John Philoponus, Fragments on the Trinity.