1 Thessalonians 5:24 - Matthew Poole's English Annotations on the Holy Bible

We had in the former verse the apostle's prayer, here his faith; and he speaks it by way of consolation to them, that what he had prayed for God would effect. What need he then have prayed? Because God's decrees and promises, though immutable and infallible, yet are to be accomplished in a way of prayer. Prayer is our duty, and God's decrees and promises are no dispensation from our duty: besides, duties are more known to us than God's decrees; and God decree the means as well as the end. But what is it he saith God will do? It is not here expressed, and the word it is not in the original, but only God will do, God will effect. He had prayed God would sanctify them wholly, and preserve them blameless, &c.; and this he would do or effect. And he grounds his confidence partly upon God's calling them. For the apostle knew that God's gifts and calling are without repentance; and whom he called, them he justified, and glorified, Romans 8:30, Romans 11:29. And this the apostle saw in these Thessalonians, by that efficacy of the gospel upon their hearts, that they were effectually called and chosen, as 1 Thessalonians 1:4; whence he concluded they should be at last wholly sanctified and finally preserved, which is a strong argument against final apostacy from a state of grace; though many that are outwardly called are never sanctified, much less wholly. But of this call the apostle speaks not here, at least not only. And partly also upon God's faithfulness, who had called them. He doth not say, God is able to do it, though that is true, but he is faithful, and will do it. Those that are effectually called are brought into God's covenant, where perfection and perseverance are promised, and God's faithfulness obligeth him to make good his covenant. It is an act of grace and mercy to call men; but when called, God's faithfulness is engaged to preserve them, and perfect the work begun: as, 1 Corinthians 1:8, the apostle tells the Corinthians, God will confirm them, to the end they might be blameless in the day of Christ; and his argument is, for God is faithful, by whom ye were called, & c., 1 Thessalonians 5:9.