The Christian Doctrine of God gives rise to a problem of more general application. How important was the influence of Greek thought upon the early Church, and how should we estimate its value?

Christians will agree that their primary inspiration is the life and teaching of Jesus Christ as presented in the New Testament. Much of this teaching was based on the sacred Scriptures as he knew them, which roughly correspond to our Old Testament. We cannot demonstrate that Jesus himself treated all these Scriptures as having equal authority and value; most Jews of his time drew a distinction between the Law, the Prophets and the Writings; and certainly few modern Christians will equate them. But a general allegiance to the Old Testament has been an indispensable part of Christian discipleship ever since the second-century Church rejected the Marcionites' attempt to discard it.

Most Christians, again, accept the judgement of the early Church in supplementing the Gospel records with other documents which reveal how the life and death of Jesus was interpreted and imitated by his followers of the next generation; the documents added to the Gospels in our New Testament. Many scholars, of course, go much further than this; for example, they regard St Paul's letters as our primary authority, since they provide contemporary evidence for the life of the Church, whereas the Gospels attempt to recall the events of a generation or two before they were written.

Christology can be defined as ‘The study of the Person of Christ, and in particular of the union in Him of the divine and human natures’. This definition relies on philosophical concepts as employed in the debates about Christ which led up to the Council of Chalcedon in 451. The ‘christology’ of the New Testament is far less formal and unified; there is no mention of a union of natures, and the key-word prosōpon usually means ‘face’ or ‘appearance’, sometimes ‘dignity’ (Matt. 22:16 etc.) but never ‘person’, except perhaps at 2 Corinthians 2:10. Our present task is to explain how the philosophical concepts were introduced, what they meant, and whether their use is justified. For this purpose we need some account of the actual development of the doctrine of Christ; but this can be reduced to a mere outline, which can easily be filled in from the standard text-books.

The New Testament embodies two contrasted pictures of Christ. In the Synoptic Gospels he is unquestionably a man. He is set apart from other men by the authority with which he spoke, his miraculous powers, the prophecies which he fulfilled, his dispensation of the Spirit, his declared fellowship with the Father, his virginal conception, and above all by his rising from the dead. But he remains a Jewish teacher, a carpenter by trade, the son of Mary, along with his brothers and sisters. By contrast, the Fourth Gospel presents him as a heavenly being come down to earth, who can speak of ‘the glory which he had with his Father before the world existed’ (John 17:5).

Christians came to characterize God as a Trinity of Father, Son and Spirit, three Persons in one substance. We shall have to explain the meaning and background of the technical terms employed here; but some larger questions call for attention. Pure monotheism is commonly thought to be one of the great achievements of Israelite religion. Why then did later Judaism apparently complicate and confuse it with a doctrine of subordinate agencies and powers? And why did Christians pick out just two of these powers, God's Word and his Spirit, connect them with their master Jesus, and associate them with the Father in a triadic or trinitarian theology? We might, perhaps, explain this process theologically, in terms of a divine providence preparing the way for the later Christian doctrine; but this would not answer our perfectly proper historical enquiry into the stages by which the transformation came about and the human reflections which it involved.

The first question could be answered in general terms by saying that the Israelites found it necessary to envisage God both as enthroned in majesty above the heavens and as intervening actively in the affairs of men, to reward, to punish, or to inspire. The early Israelites pictured God as himself coming down and appearing in human form (see p. 100 above); but it was clearly naive to suppose that God could absent himself from heaven and attend exclusively to some particular human crisis. It was then supposed that God acts at a distance through the medium of subordinate spiritual beings, the angels.

Gregory of Nazianzus has the confidence to demand ‘Are not spirit and fire and light, love and wisdom and righteousness, and mind and reason and the like, names of the First Nature?’ (Orat. 28.13). He goes on to point out that all these names can convey misleading suggestions. Nevertheless they were firmly rooted in Christian tradition. Hence, as we have shown, the common descriptions of God as ‘unknowable’ or ‘indescribable’ are not to be pressed in a literal sense; they do not debar us from shadowing out God's nature by using words drawn from our everyday experience. These words, indeed, could not be avoided, in view of the biblical texts which describe God as Fire, Light, Life, etc. (Deut. 4:24, 1 John 1:5, John 1:4, etc.). But reinterpretation is needed, and the Christian writers tend to refine such bold metaphors; very commonly they retain the notion that God is mind or intelligence, and interpret the other terms as indicating dispositions or activities of the divine mind. At the same time, Neoplatonist philosophers were debating whether or not nous was the proper designation of the First Principle.

It is convenient to distinguish the predicates applied to God as metaphysical and natural, the latter group including both physical and moral terms. Within the first group we have dealt briefly with the descriptions of God as Being, as Unity, and as ultimate Source (Jer. 2:13 etc.). We must now consider the attributes of Mind and Spirit.

Augustine's three books On Free Will have a controversial purpose and are mainly aimed against Manichaeism; his central concern is the problem of evil, which the Manichees regarded as a cosmic principle comparable in power with God himself. Augustine has two distinguishable forms of reply, neither of them wholly original, but both developed with persuasive skill. In the first, he claims that our main concern is with moral evil. Like other thinkers, Augustine distinguishes two forms of evil, sin and suffering; but suffering, he claims, is the just punishment for the sin which man has committed at and after the Fall. Was it right, then, for God to create a world in which men could sin? Augustine answers that sin is a misuse of free will, and without free will there can be no virtuous conduct; God did right, therefore, in creating man free. Embedded in this argument is the claim that sin consists in the choice of lesser goods when greater ones should have been preferred; in particular, of course, bodily pleasures rather than spiritual benefits (op. cit. 2.48–54). Evil of this kind can arise in a world which is wholly good, as befits God's creation; no blame attaches to God for creating a world where there are different degrees of goodness; indeed such variety enhances its perfection as a whole. It is men who are to blame for choosing the lesser goods (3.5.12–3.6.18; cf. Civ. Dei 11.16–18, 12.4–5, etc.).

As literature, the dialogues of Plato's middle period are among the world's greatest creative achievements; the later dialogues fall short of them in imaginative power and dramatic skill. Nevertheless they advance considerations of great importance for the future of logic and metaphysics. Plato was now much concerned with the theory of knowledge. A fairly early dialogue, the Meno, had pointed the way; Meno, an intelligent but uneducated slave, is questioned by Socrates and shown to discover a simple mathematical truth without being told. Some truths, then, can be known independently of experience; and Plato concludes that the soul became acquainted with the Forms in a previous existence which we have forgotten; the discovery of such truths is in fact a recollection (anamnēsis). This clearly marks a distinction between knowledge of the Forms and knowledge of everyday facts; but the proof of our pre-existence gives little support to the theory of transmigration, which Plato presents in several dialogues with a wealth of imaginative detail; for we are said to recollect a previous ideal existence, whereas the transmigration theory would make it probable that other imperfect incarnations have preceded our present life.

In the Theaetetus, where the problem of knowledge is more fully discussed, there is surprisingly little reference to the Forms; but the dialogue is important, inter alia, for its demonstration that perceptual knowledge involves more than mere perception, and again for the suggestion that knowledge is a disposition; knowing is not something like seeing or sleeping which we do from time to time; to know something is to be able to act or answer correctly when required.

Christian writers naturally turned to the Bible for their teaching on the nature of God. But their use of it was often influenced by the philosophical thought of their own day. The Hebrews, we saw in Chapter 9, pictured the God whom they worshipped as having a body and mind like our own, though transcending humanity in the splendour of his appearance, in his power, his wisdom, and the constancy of his care for his creatures. Such a conception, set out in the earlier books of the Old Testament, retained its authority despite some later changes of emphasis. But this biblical view, we noted on p. 58, was radically modified in the teaching of Philo of Alexandria. Philo, a devout Jew, does indeed insist on God's moral attributes: his patience, his wisdom and his loving care. But he also presents him as the metaphysical first principal of the universe, without bodily form or human passions, indeed without any sensible qualities: a perfectly simple, unchangeable, unfathomable being, who can only be positively described in the words of Exodus 3:14 as ‘He who Is’.

Christian writers developed a broadly similar view, partly because they were influenced by the same philosophical authorities, partly through direct imitation of Philo himself. To this they added their doctrine of the Trinity, which will concern us later; here too their thinking was influenced by Philo, especially in his conception of the divine Logos; but there was less in the way of actual borrowing.

Plato's most important pupils were his nephew Speusippus, who succeeded him as head of the Academy on his death in 347; Xenocrates, who followed Speusippus, 339–314; and Aristotle, who broke away from Plato's influence and after spending a period away from Athens returned in 335 to found a school of his own, the Lyceum. Meanwhile he had acted as tutor to the young Alexander the Great. On Alexander's death in 323 an anti-Macedonian movement in Athens induced him to leave the city, and he died the next year.

Aristotle's influence on Western thought can hardly be exaggerated; but he was not a major influence on Christianity during its first four centuries, and for that reason will be rather briefly treated here. Indeed the scope and originality of his thought were not generally appreciated for several centuries after his death. The reasons for this change of fortune can be found in the history of his writings.

The works which were accessible to early Christians and other non-specialist enquirers were in the main those which he called his ‘exoteric’ or popular writings, which though lacking Plato's literary genius were carefully written to appeal to the general reader. These works have not survived, though to some extent they can be reconstructed from surviving fragments. It appears that they were written early in life, while Plato's influence was still powerful, and that they take an idealistic view of the aims of philosophy, besides showing signs of personal religious feeling.

During some four centuries in late antiquity, from the second till early in the fifth, two systems of belief and moral direction existed side by side. At the start of this period well-educated men in civilized Europe looked to philosophy for guidance; as we have seen, the Platonic tradition was already strong and would soon be dominant. Philosophy was taken to comprise logic, ethics and physics, which included the beginnings of what we now call natural science. Ancient logic led up to the theory of knowledge; ethics enquired what sorts of good we should aim at securing, and how to achieve them in practice.

At the outset of this period Christianity did not look like a counterpart to philosophy; indeed it was not always recognized as a distinct movement independent of the Judaism from which it sprang. But it developed very rapidly, and by the end of our period it had captured the intellectual allegiance of cultivated citizens in both the Eastern and the Western Empire. Compared with other religions of its time and place it was far more successful in organizing its beliefs into a coherent system. In doing this it borrowed largely from philosophy, and especially from Platonism. But it kept a sharply defined identity; its commitment to the Bible as a sacred book was far more uncompromizing than the philosophers' respect for Plato; and it valued communal experience and tradition in a way which offended students accustomed to accepting the guidance of expert scholars. Nevertheless philosophy helped to mould its beliefs about God and the world, and taught it to uphold them in argument.

Augustine is by far the ablest philosopher of late antiquity. He is also one of its best-known characters; he reveals his inmost thoughts at many points in his voluminous writings, but particularly in the Confessions, which recalls his early life and his conversion, and in the Retractations, one of his last productions, in which he gives a chronological survey of his written work and explains the corrections which he now wishes to establish. More than most ancient writers, his thought underwent a development which is closely related to his changing occupations and concerns. This makes it difficult to capture in a brief account; all its phases are interesting and worthy of note. And there is a particular difficulty in treating of Augustine as a philosopher. The enormous literature he has inspired of course includes examinations of his philosophical thought; but the great majority of these are written by admirers, who moreover share the basic assumptions of his metaphysics. Many modern philosophers, at least in the Anglo-Saxon tradition, reject these assumptions altogether, or in large part, as I am impelled to do myself, and are thus bound to be handicapped in providing a survey which is at once appreciative, scholarly and critical.

Augustine was born in 354 at Tagaste in North Africa, about 200 km west of Carthage and some 700 km south-west of Rome. His father Patricius was a pagan till late in life, his mother Monica a Christian.

Christian theology begins with the New Testament. The earliest Christians, it shows us, were ready to expound the Scriptures and to defend their faith in Jesus against Jewish and pagan opponents. But before long they faced the new task of expressing their beliefs in a way that well-educated pagans could understand and appreciate. And as the Christian movement expanded, new expressions of the faith were devised, and had to be examined and approved so that as far as possible disagreements and misconceptions could be avoided. The great development of early Christian theology took place in the three hundred years extending from the mid-second century to the Council of Chalcedon in 451: the age of Irenaeus, Origen, Athanasius and Augustine.

At this time the various schools of philosophy gave their adherents many of the benefits we now expect from religion. The conventional state religion was often little more than a formality; the so-called ‘mystery cults’ offered comfort and reassurance, but provided no explanations and made few demands; the worshipper could enter one, two or several such fellowships as he wished. The Jews had largely detached themselves from the main stream of ancient culture. It was the philosophers who both called for commitment and presented a way of life based on a rational view of the world and man's place within it.

Philosophy was invented and given to the world by the Greeks. Although in some departments they drew on the experience of other nations (for instance, on Babylonian astronomy), it was the Greeks who developed philosophy into a wide complex of studies, which included the beginnings of what we now call natural science, and which was later to be summed up in the three headings of logic, ethics and physics. Physics was the name given to the study of the natural world and its explanatory principles; it therefore took in the question whether there are gods, or a single God, and whether the world was made, and is governed, by such beings. For those who believed in divine existence, theology was a branch of physics.

The Greek philosophers broke new ground through their ability to ask abstract and wide-ranging questions. Before their time, much common-sense observation was embodied in the working knowledge of sailors, farmers and builders, or expressed in proverbial sayings about human conduct. But for the large general questions about the world men had to resort to a primitive mythology which associated each of the main components of the world with a particular divine being; the heavens with Zeus, the sea with Poseidon, and so on. A philosophy recognizably distinct from mythology began when the sages of Miletus, in Asia Minor, attempted to explain the world in terms of inanimate things which could be expected to behave in a regular way in accordance with a few simple laws.

Plato is probably the greatest of the Greek philosophers; without question he made the greatest contribution to Christian theology. Not that he himself set out to expound a system or doctrine; his genius lay rather in raising profound and far-reaching questions in an informal style with the minimum of technical terms. To some of these questions he gave definite answers; in many cases he was content to demonstrate the complexity of a problem and the considerations to be borne in mind, partly as an exercise in rational discussion, but mainly from a deeply serious conviction of the difficulty of attaining the whole truth, and a dislike of premature solutions. The later Platonist philosophers seldom imitated this open, undogmatic approach, but made selections from his writings which seemed relatively consistent and could be defended against opposing schools. Among Christians an open, uninhibited approach to philosophy was revived for a time, especially under the influence of the Alexandrians Clement and Origen, in the third and fourth centuries, when bold speculations could be excused as ‘exercises’, gymnasiai; and in this period the influence of Platonist writers made itself felt on Christian theology. But this in turn developed a fixed dogmatic outline, reinforced by the authoritative decisions of Church councils. From that time on most Christians quoted Plato solely where he appeared to confirm established doctrines of the Church; the reality of God, his creation and providence, the heavenly powers, the human soul, its training, survival and future judgement, could all be upheld by appropriate choice of Platonic texts.