=The Philosophies influencing Christian Thought.= The Greek philosophies most influential upon the development of Christian doctrine were Stoicism and neo-Platonism. The philosophy of Philo was also influential, but it was really only a bridge from philosophical Judaism to Christian theology. It contained both Stoicism and Platonism in an unsymmetrical form, and Philo’s writings “contain the seeds of nearly all that afterwards grew up on Christian soil.”[44] Greek philosophical influence upon the early Christian world was felt in two ways: in ethical theory and practice; in the construction of theology. During the fourth century Stoic ethics of a Cynic type replaced the early Christian ethics. The basis of Christian society was no longer the ethics of the Sermon on the Mount, but rather that of Roman Stoicism. This is shown by the character of that book on morals (_De Officiis Ministrorum_) by St. Ambrose, Bishop of Milan (340–397). In theology the Christian doctrine had no need to borrow from the Greeks the conception of the unity of God or that of the creation of the world by God. But the Greek influence is seen in the doctrines on subjects allied to these: mainly on the questions of _the mode of creation_ and _the relation of God to the material world_. In the discussion of these questions the influence of the Stoic monism, tending toward dualism, and the influence of Platonic dualism, tending toward a threefold conception of God, Matter, and Form, will appear in the examples which subsequently follow. The most formidable opponent of Christianity during this time was neo-Platonism, but neo-Platonism and Christianity were not, however, long separated. Although neo-Platonism met its fate at the hands of scholasticism, it influenced in a thousand ways both orthodox and heretical Christianity. The rivalry of these two bodies ended――and with it came the ending of the Hellenic-Roman period of philosophy――in a complete and original theology. This was the theology of St. Augustine, who marks the end of antiquity and the beginning of the Middle Ages. =The Periods of Early Christianity= (30 A. D.–476 A. D.). 1. Introductory Period, 30–200. (1) Period of Primitive Faith (during the 1st century A. D.). With great simplicity of doctrine and ceremonies the Christians were preparing through faith and the practice of virtue for the Second Coming of our Lord. (2) Period of the Earlier Formulation and Defense of Christian Doctrine (during the 2d century A. D.). (a) The Apologists (2d century). (b) The Gnostics (2d century). (c) The Old Catholic Theologians (2d and 3d centuries).