Immortality of the Body
Jesus Christ Himself, who is the Lord and Creator of the soul, is said to be the clothing of the saints, “Put ye on the Lord Jesus Christ.”(Rom.13;14) As Christ, then, is the clothing of the soul, so is the soul said to be the clothing of the body, seeing it is an ornament to it, covering and concealing its mortal nature…a soul possessing in itself incorruptibility, because it has been clothed with Christ, who is the Wisdom, Word and Righteousness of God, which mould, and clothe, and adorn the soul, But when this body, which at some future period we shall possess in a more glorious state, shall have become a partaker of life, it will then, in addition to being immortal, become also incorruptible. For whatever is mortal is necessarily also corruptible; but whatever is corruptible cannot also be said to be mortal. We say of a stone or a piece of wood that it is corruptible, but we do not say that it follows that it is also mortal. But as the body partakes of life, then because life may be, and is, separated from it, we consequently name it mortal, and according to another sense also we speak of it as corruptible.
Incorporeity
Nothing else than a material nature is to be destroyed, on which death could operate, while the mental acumen of those who are in the body seems to be blunted by the nature of corporeal matter. If, however, they are out of the body, then they will altogether escape the annoyance arising from a disturbance of that kind. But as they will not be able immediately to escape all bodily clothing, they are just to be considered as inhabiting more refined and purer bodies, which possess the property of being no longer overcome by death, or of being wounded by its sting; so that at last, by the gradual disappearance of the material nature, death is swallowed up … by the divine grace which the soul has been rendered capable of receiving, and has thus deserved to obtain incorruptibility and immortality. “O death, where is thy victory? O death, where is thy sting? The sting of death is sin.” If these conclusions hold good, it follows that we must believe our condition at some future time to be incorporeal; and if all are said to be subjected to Christ, this (incorporeity) also must necessarily be bestowed on all to whom the subjection to Christ extends; and bodily matter returns to nothing, as formerly also it did not exist.
Incarnation
That soul (anima) regarding which Jesus said, “No one shall take my life (animam) from me,” inhering, from the beginning of the creation, and afterwards, inseparably and indissolubly in Him, as being the Wisdom and Word of God, and the Truth and the true Light, and receiving Him wholly, and passing into His light and splendour, was made with Him in a pre-eminent degree one spirit, according to the promise of the apostle to those who ought to imitate it, that “he who is joined in the Lord is one spirit.” This substance of a soul, then, being intermediate between God and the flesh—it being impossible for the nature of God to intermingle with a body without an intermediate instrument—the God-man is born,
And therefore deservedly is it also called, along with the flesh which it had assumed, the Son of God, and the Power of God, the Christ, and the Wisdom of God, either because it was wholly in the Son of God, or because it received the Son of God wholly into itself. And again, the Son of God, through whom all things were created, is named Jesus Christ and the Son of man. For the Son of God also is said to have died—in reference, viz., to that nature which could admit of death; and He is called the Son of man, who is announced as about to come in the glory of God the Father, with the holy angels.
“Thou hast loved righteousness, and hated wickedness: therefore God, thy God, hath anointed thee with the oil of gladness above thy fellows.” As a reward for its love, then, it is anointed with the oil of gladness; i.e., the soul of Christ along with the Word of God is made Christ. Because to be anointed with the oil of gladness means nothing else than to be filled with the Holy Spirit. And when it is said “above thy fellows,” it is meant that the grace of the Spirit was not given to it as to the prophets, but that the essential fulness of the Word of God Himself was in it, according to the saying of the apostle, “In whom dwelt all the fulness of the Godhead bodily.”
But since the power of choosing good and evil is within the reach of all, this soul which belonged to Christ elected to love righteousness, so that in proportion to the immensity of its love it clung to it unchangeably and inseparably, so that firmness of purpose, and immensity of affection, and an inextinguishable warmth of love, destroyed all susceptibility (sensum) for alteration and change; and that which formerly depended upon the will was changed by the power of long custom into nature; and so we must believe that there existed in Christ a human and rational soul, without supposing that it had any feeling or possibility of sin.
With regard to the soul of the Saviour, that of those things which are written in the Gospel, some are ascribed to it under the name of soul, and others under that of spirit. For when it wishes to indicate any suffering or perturbation affecting Him, it indicates it under the name of soul; as when it says, “Now is My soul troubled;” and, “My soul is sorrowful, even unto death;” and, “No man taketh My soul from Me, but I lay it down of Myself.” Into the hands of His Father He commends not His soul, but His spirit; and when He says that the flesh is weak, He does not say that the soul is willing, but the spirit: whence it appears that the soul is something intermediate between the weak flesh and the willing spirit.
–On First Principles Bk. II