1 Thessalonians 3:13

To the end he may stablish your hearts
Which are very unstable and inconstant in their frames, and in the exercise of grace, and have need to be established in the love of God, against the fears of men, the frowns of the world, the temptations of Satan, and in, and with the doctrines of grace; (See Gill on 1 Thessalonians 3:2),

unblamable in holiness before God, even our Father.
There is no holiness in men naturally; what is in them without the grace of God is only a show; true holiness is from the Spirit of God; and this is a stable thing in itself, and can never be removed or taken away; but the acts of it, through the prevalence of corruption, the force of Satan's temptations, and the snares of the world, are fickle and inconstant; and the saints need to be established in the discharge of duty, as well as in the exercise of grace: and whereas the apostle prays, that they might be "unblamable in holiness", the Alexandrian copy reads, "in righteousness" so one of Stephens's; it must be observed, that no man is perfectly holy in this life; no man is without sin in himself, or lives without the commission of it; holiness in the best is imperfect; no man, as yet, is in himself sanctified wholly; there is no unblamable holiness but in Christ; and in him the saints are without spot and blemish, who is their sanctification and their righteousness; but in themselves they are full of spots and stains; yet through the grace of God their hearts may be so established with principles of holiness, and they may be so assisted in the acts of it daily, as to give no just cause of blame to men, and so to behave as to approve themselves "before God", who sees the heart, and knows from what principles all actions flow: and this the apostle desires may be at the coming of our Lord Jesus; or unto the coming of him, as in ( 1 Thessalonians 5:23 ) Either at death, when he comes into his garden, and gathers his lilies, and takes his to himself to be for ever with him; or at the day of judgment, when he comes to judge the quick and dead; and which coming of his is certain, and will be quickly and suddenly, and with great glory and power: and, as it is here added,

with all his saints;
meaning either his holy angels, or rather the souls of his people, whom he will bring with him, and will raise their dead bodies, and reunite them to their souls, when they shall be for ever with him; and then shall they be unblamable in holiness, both in soul and body, and shall be presented by him, first to himself, and then to his Father, faultless, and without spot, or wrinkle, or any such thing. The Vulgate Latin, Arabic, and Ethiopic versions add, "Amen"; and so does Beza's ancient copy, and the Alexandrian manuscript.