Being confident of this very thing, that he which has begun a good work in you will perform it until the day of Jesus Christ:
These words, found linked together more than once in Pauline usage, e.g., 2 Corinthians 8:6, Galatians 3:3, have probably a sacrificial import. They are used in describing religious ceremonials, and especially the ritual of sacrifice. The metaphor then may be this: just as a sacrifice, when once it is solemnly inaugurated, is carried through with all the appropriate rites to its completion, so every work of grace in the believer's heart, being not only God's work, but a work which is an offering presented unto Him, will be carried on to its proper consummation. Nothing will be allowed to come in the way, so as to render it a half-finished, a mutilated, an imperfect thing. Begun, it must be "performed." Paul is now writing to a Christian community composed for the most part of those who had once been heathen; his language therefore purposely takes appropriate colouring from their former but now forsaken rites. There is, he would say, a sacrifice carried on within their souls, a work of grace, a work shown in Christian liberality, which God will not permit to remain mutilated and incomplete. This explanation is all the more probable in view of a similar figure found in Philippians 2:17. There substantially the same metaphor appears distinctly on the surface, which at least lies only hidden here. It reminds us of the infinite solemnity belonging to every good work wrought within us and wrought by us. It is "an odour of a sweet smell, a sacrifice acceptable, well pleasing to God." But the apostle directs the thought forward to the final completion of this service, "until the day of Jesus Christ."
(J. Hutchinson, D. D.)
Parallel VersesKJV: Being confident of this very thing, that he which hath begun a good work in you will perform it until the day of Jesus Christ: