This is a prayer of Paul's in which he makes a bold request on behalf of that congregation. It contains great encouragement for us. Paul requests their complete sanctification and preservation as holy until they die or God finishes His activities on behalf of the church at Christ's coming.
Sanctification is the part of salvation that deals with our progressive growth in the grace and the knowledge of Jesus Christ—or put another way, to the measure of the stature of the fullness of Christ—or in yet another way, into God's image. God is faithful in carrying out His part in the building of Christian character. God's faithfulness guarantees the progressive perfection of a Christian's life. He is not like men who begin a project, lose interest, run into difficulties, consider it too hard to overcome, or become impatient and quit. He does not begin a work and then get disgusted with it and turn to something else. He does not begin and, finding He lacks the resources to finish, give up. Men do this, but God never stops until He is finished. He does not finish until He is satisfied.
John W. Ritenbaugh
The Fruit of the Spirit: Faithfulness
Other Forerunner Commentary entries containing 1 Thessalonians 5:24:
1 Corinthians 9:19-22