On Why Angels Can’t Repent

Heb 2:16-17 For surely it is not angels that He helps, but he helps the offspring of Abraham. Therefore he had to be made like his brothers in every respect, so that he might become a merciful and faithful high priest in the service of God, to make propitiation for the sins of the people.

Tertullian of Carthage ca. 160-220

Let us now consider its special relation to Christianity, and see how vast a privilege before God has been conferred on this poor and worthless substance. It would suffice to say, indeed, that there is not a soul that can at all procure salvation, except it believe while it is in the flesh, so true is it that the flesh is the very condition on which salvation hinges. And since the soul is, in consequence of its salvation, chosen to the service of God, it is the flesh which actually renders it capable of such service. The flesh, indeed, is washed, in order that the soul may be cleansed; the flesh is anointed, that the soul may be consecrated; the flesh is signed (with the cross), that the soul too may be fortified; the flesh is shadowed with the imposition of hands, that the soul also maybe illuminated by the Spirit; the flesh feeds on the body and blood of Christ, that the soul likewise may fatten on its God. (On the Resurrection of the Flesh 8)

St. John Damascene ca. 676-749

The angel’s nature then is rational, and intelligent, and endowed with free-will, changeable in will, or fickle. For all that is created is changeable, and only that which is un-created is unchangeable. Also all that is rational is endowed with free-will. As it is, then, rational and intelligent, it is endowed with free-will: and as it is created, it is changeable, having power either to abide or progress in goodness, or to turn towards evil.

It is not susceptible of repentance because it is incorporeal. For it is owing to the weakness of his body that man comes to have repentance. (An Exact Exposition of the Orthodox Faith Bk. II.3)