Texts Explained; Secondly, Psalm 45:7, 8.--> Whether the words 'therefore,' 'anointed,' etc., imply that the Word has been rewarded. Argued against first from the word 'fellows' or 'partakers.' He is anointed with the Spirit in His manhood to sanctify human nature. Therefore the Spirit descended on Him in Jordan, when in the flesh. And He is said to sanctify Himself for us, and give us the gloryHe has received. The word 'wherefore' implies His divinity. 'You have loved righteousness,' etc., do not imply trial or choice
51 Nor do the words, 'You have loved righteousness and hated iniquity,' which are added in the Psalm, show, as again you suppose, that the Nature of the Word is alterable, but rather by their very force signify His unalterableness. For since of things originate the nature is alterable, and the one portion had transgressed and the other disobeyed, as has been said, and it is not certain how they will act, but it often happens that he who is now good afterwards alters and becomes different, so that one who was but now righteous, soon is found unrighteous, wherefore there was here also need of one unalterable, that men might have the immutability of the righteousness of the Word as an image and type for virtue. And this thought commends itself strongly to the right-minded. For since the first man Adam altered, and through sin death came into the world, therefore it became the second Adam to be unalterable; that, should the Serpent again assault, even the Serpent's deceit might be baffled, and, the Lord being unalterable and unchangeable, the Serpent might become powerless in his assault against all. For as when Adam had transgressed, his sin reached unto all men, so, when the Lord had become man and had overthrown the Serpent, that so great strength of His is to extend through all men, so that each of us may say, 'For we are not ignorant of his devices. ' Good reason then that the Lord, who ever is in nature unalterable, loving righteousness and hating iniquity, should be anointed and Himself sent, that, He, being and remaining the same, by taking this alterable flesh, 'might condemn sin in it,' and might secure its freedom, and its ability henceforth 'to fulfil the righteousness of the law?' in itself, so as to be able to say, 'But we are not in the flesh but in the Spirit, if so be that the Spirit of God dwells in us.'
52. Vainly then, here again, O Arians, have you made this conjecture, and vainly alleged the words of Scripture; for God's Word is unalterable, and is ever in one state, not as it may happen, but as the Father is; since how is He like the Father, unless He be thus? Or how is all that is the Father's the Son's also, if He has not the unalterableness and unchangeableness of the Father? Not as being subject to laws, and biassed to one side, does He love the one and hate the other, lest, if from fear of falling away He chooses the one, we admit that He is alterable otherwise also; but, as being God and the Father's Word, He is a just judge and lover of virtue, or rather its dispenser. Therefore being just and holy by nature, on this account He is said to love righteousness and to hate iniquity; as much as to say, that He loves and chooses the virtuous, and rejects and hates the unrighteous. And divine Scripture says the same of the Father; 'The Righteous Lord loves righteousness; Thou hatest all them that work iniquity,' and 'The Lord loves the gates of Sion, more than all the dwellings of Jacob;' and, 'Jacob have I loved, but Esau have I hated;' and in Isaiah there is the voice of God again saying, 'I the Lord love righteousness, and hate robbery of unrighteousness.' Let them then expound those former words as these latter; for the former also are written of the Image of God: else, misinterpreting these as those, they will conceive that the Father too is alterable. But since the very hearing others say this is not without peril, we do well to think that God is said to love righteousness and to hate robbery of unrighteousness, not as if biassed to one side, and capable of the contrary, so as to select the latter and not choose the former, for this belongs to things originated, but that, as a judge, He loves and takes to Him the righteous and withdraws from the bad. It follows then to think the same concerning the Image of God also, that He loves and hates no otherwise than thus. For such must be the nature of the Image as is Its Father, though the Arians in their blindness fail to see either that image or any other truth of the divine oracles. For being forced from the conceptions or rather misconceptions of their own hearts, they fall back upon passages of divine Scripture, and here too from want of understanding, according to their wont, they discern not their meaning; but laying down their own irreligion as a sort of canon of interpretation, they wrest the whole of the divine oracles into accordance with it. And so on the bare mention of such doctrine, they deserve nothing but the reply, 'You do err, not knowing the Scriptures nor the power of God;' and if they persist in it, they must be put to silence, by the words, 'Render to' man 'the things that are' man's, 'and to God the things that are' God's.
Source: Four Discourses Against the Arians (New Advent)