As so often in the epistles, here too Paul completely rules out all human claims to merit. Salvation is a free gift. It originates entirely from God and not at all from the will or actions of man. If indeed the Christian voluntarily corrects his conduct and advances in sanctification, it is because God gives him the ability and the will. True enough, we work out our salvation in fear and trembling, but we do so because God works in us both to will and to do, and this divine working depends solely on God's good pleasure. -- Gordon H. Clark.
Commentaries on Paul's Epistles: Ephesians. (Unicoi: Trinity Foundation, 1985), page 27. [Cf. Ephesians 1:6 KJV].