For instance, his progressive stress on the Unity of the Godhead in Father, Son, and Spirit is but the following up of the thought expressed de Incarn.17.1 en mono to heautou Patri holos on kata panta. It may be noted that he argues also from the idea of the Trinity to the coessential Godhead of the Spirit, ad Serap. i.28, sq., Trias de estin ouch heos onomatos monon...alla alethei& 139; kai huparxei trias...eipatosan palin...trias estin e duas; and that he meets the difficulty (see infra, p.438, ten lines from end, also Petav. Trin. VII. xiv.) of differentiating the relation of the Spirit to the Father from the gennesis of the Son by a confession of ignorance and a censure upon those who assume that they can search out the deep things of God (ib.17-19). The principle might be applied to this point which is laid down de Decr.11, that an act' belonging to the essence of God, cannot, by virtue of the simplicity of the Divine Nature, be more than one: the act' therefore of divine gennesis (the nature of which we do not know) cannot apply to the Spirit but only to the Son. But I do not recollect any passage in which Athanasius draws this conclusion from his own premises. The language of Athanasius on the procession of the Spirit is unstudied. In Exp. Fid.4, he appears to adopt the procession' of the Spirit from the Father through the Son (after Dionysius, see Sent. Dion.17). In Serap. i.2, 20, 32, iii.1, he speaks of the Spirit as idion tou Logou, just as the Word is idios tou Patros. His language on the subject, expressing the idea common to East and West (under the cloud of logomachies which envelop the subject) might possibly furnish the basis of an eirenicon' between the two separated portions of Christendom. In explaining the theophanies' of the Old Testament, Athanasius takes a position intermediate between that of the Apologists, &c. (supr., p. xxiii.) who referred them to the Word, and that of Augustine who referred them to Angels only. According to Athanasius the Angel' was and was not the Word: regarded as visible he was an Angel simply, but the Voice was the Divine utterance through the Word (see Orat. iii.12, 14; de Syn.27, Anath 15, note; also Serap. i.14).
Lastly, it must again be insisted that in his polemic against Arianism Athanasius is centrally soteriological. It is unnecessary to collect passages in support of what will be fully appreciated only after a thorough study of the controversial treatises. The essence of his position is comprised in his paraphrase of St. Peter's address to the Jews, Orat. ii.16, sq., or in the argument, ib.67, sqq., i.43, and iii.13. With regard to the Incarnation, it may be admitted that Athanasius uses language which might have been modified had he had later controversies in view. His common use of anthropos for the Manhood of Christ (see below, p.83) might be alleged by the Nestorian, his comparison of it to the vesture of the High Priest (Orat. i.47, ii.8, see note there) by the Apollinarian or Monophysite partisan. But at least his use of either class of expressions shews that he did not hold the doctrine associated in later times with the other. Moreover, while from first to last he is explicitly clear as to the seat of personality in Christ, which is uniformly assigned to the Divine Logos (p.40, note 2 and reff.), the integrity of the manhood of Christ is no less distinctly asserted (cf. de Incarn.18.1, 21.7). He uses soma and anthropos indifferently during the earlier stages of the conflict, ignoring or failing to notice the peculiarity of the Luciano-Arian Christology. But from 362 onward the full integrity of the Saviour's humanity, sarx and psuche logike or pneuma, is energetically asserted against the theory of Apollinarius and those akin to it  (cf. Letters 59 and 60, and c. Apoll.). Some corollaries of this doctrine must now be mentioned.
The question of the sinlessness of Christ is not discussed by Athanasius ex professo until the controversy with Apollinarianism. In the earlier Arian controversy the question was in reality involved, partly by the Arian theory of the preptotes of the Word, partly by the correlated theory of prokope (cf. Orat. ii.6, sqq.), and Athanasius instinctively falls back on the consideration that the Personality of the Son, if Divine, is necessarily sinless. In c. Apoll. i.7, 17, ii.10 the question is more thoroughly analysed. The complete psychological identity of Christ's human nature with our own is maintained along with the absolute moral identity of His will (thelesis, the determination of will, not the thelema ousiodes or volitional faculty) with the Divine will.
With regard to the human knowledge of Christ, the texts Mark xiii.32, Luke ii.52, lie at the foundation of his discussion Orat. iii.42-53. The Arians appealed to these passages to support the contention that the Word, or Son of God in His Divine nature, was ignorant of the Day,' and advanced in knowledge. The whole argument of Athan. in reply is directed to shewing that these passages apply not to the Word or Son in Himself, but to the Son Incarnate. He knows as God, is ignorant as man. Omniscience is the attribute of Godhead, ignorance is proper to man. The Incarnation was not the sphere of advancement to the Word, but of humiliation and condescension; but the Manhood advanced in wisdom as it did in stature also, for advance belongs to man. That is the decisive and clear-cut position of Athanasius on this subject (which the notes there vainly seek to accommodate to the rash dogmatism of the schools). Athanasius appeals to the utterances of Christ which imply knowledge transcending human limitations in order to shew that such knowledge, or rather all knowledge, was possessed by the Word; in other words such utterances belong to the class of divine' not to that of human' phenomena in the life of Christ. So far as His human nature was concerned, He assumed its limitations of knowledge equally with all else that belongs to the physical and mental endowments of man. Why then was not Divine Omniscience exerted by Him at all times? This question is answered as all questions must be which arise out of any limitation of the Omnipotence of God in the Manhood of Christ. It was for our profit, as I at least think' (ib.48). The very idea of the Incarnation is that of a limiting of the Divine under human conditions, the Divine being manifested in Christ only so far as the Wisdom of God has judged it necessary in order to carry out the purpose of His coming. In other words, Athanasius regarded the ignorance of Christ as economical' only in so far as the Incarnation is itself an oikonomia, a measured revelation, at once a veiling and a manifestation, of all that is in God. That the divine Omniscience wielded in the man Christ Jesus an adequate instrument for its own manifestation Athanasius firmly holds: the exact extent to which such manifestation was carried, the reserve of miraculous power or knowledge with which that Instrument was used, must be explained not by reference to the human mind, will, or character of Christ, but to the Divine Will and Wisdom which alone has both effected our redemption and knows the secrets of its bringing about. With Athanasius, we may quote St. Paul, tis egno noun Kuriou.
It may be observed before leaving this point that Athanasius takes occasion (§43, fin., cf.45) to distinguish two senses of the words the Son,' as referring on the one hand to the eternal, on the other to the human existence of Christ. To the latter he limits Mark xiii.32: the point is of importance in view of his relation to Marcellus (supra, p. xxxvi.).
As a further corollary of the Incarnation we may notice his frequent use (Orat. iii.14, 29, 33, iv.32, c. Apoll. i.4, 12, 21) of the word theotokos as an epithet or as a name for the Virgin Mary. The translation Mother of God' is of course erroneous. God-bearer' (Gottes-bärerin), the literal equivalent, is scarcely idiomatic English. The perpetual virginity of Mary is maintained incidentally (c. Apoll. i.4), but there is an entire absence in his writings not only of worship of the Virgin, but of Mariology,' i.e., of the tendency to assign to her a personal agency, or any peculiar place, in the work of Redemption (Gen. iii.15, Vulg.). Further, the argument of Orat. i.51 fin., that the sending of Christ in the flesh for the first time (loipon) liberated human nature from sin, and enabled the requirement of God's law to be fulfilled in man (an argument strictly within the lines of Rom. viii.3), would be absolutely wrecked by the doctrine of the freedom of Mary from original sin (immaculate conception'). If that doctrine be held, sin was condemned in the flesh' (i.e., first deposed from its place in human nature, see Gifford or Meyer-Weiss in loc.), not by the sending of Christ, but by the congenital sinlessness of Mary. If the Arians had only known of the latter doctrine, they would have had an easy reply to that powerful passage.
 The doctrine of Athanasius is, not formally but none the less really, the doctrine of Chalcedon, which again stands or falls together with that of Nicæa. Like the latter, it transcends the power of human thought to do more than state it in terms which exclude the (Nestorian and Monophysite) alternatives. The Man Jesus Christ is held to have lacked nothing that constitutes personality in man; the human personality which therefore belongs to it ideally, being in fact merged in the Divine personality of the Son. The impersonality,' as it is sometimes called, of Christ quâ man is therefore better spoken of as His Divine Personality. Personality and will are correlated but not identical ideas.