William Burkitt on Ephesians 2:8

In these words our apostle informs the Ephesians, and in them all succeeding Christians, that their complete salvation, from the first to the last, from the lowest to the highest step, depends upon God's free favour and grace in Christ, and not upon any merit or desert in ourselves; works having no meritorious or casual influence upon our salvation, (for they are not causes, but effects, of that grace by which we are saved,) to the intent that all boasting may be excluded, and that all the saints' glorying may be in God, and not in themselves.

Note here, 1. That believers are saved already, in some sense; not only because they have salvation begun in their new birth here, but they have already a right and title to, yea, a pledge and an earnest of, complete salvation; believers are saved here.

Note, 2. That the believers' salvation is through faith in Jesus Christ.

Note 3. That faith, by and through which they are said to be saved, is not of themselves, it is the gift of God; faith is the gift of God as well as Jesus Christ, and the one as necessary as the other; for as the only way to heaven is by Christ, so the only way to Christ is by faith; as sin has put a vanity into the creature, so unbelief puts a vanity in Christ, that he should profit us nothing. Wrestle we then with God in prayer for a believing heart.