Therefore Achish believed in David, etc. The entire fraternity of the nations believes in Christ, saying that the people in which He was born He abandoned due to their infidelity; and because of this infidelity, threw down so many branches of the good olive tree, so that by believing it might graft itself in, and cast those to be burned into the fire. Indeed, for me now believing, hoping, loving, He is the debtor of eternal life; so that without Him I can do nothing, both in the present the pledge of the Spirit, and in the future He will provide me with the eternal grace of His protection. Concerning this perpetual servitude bestowed upon faithful servants by God the Lord, the Lord Himself says: Amen I say to you, He will gird Himself, and will make them sit down to eat, and passing will minister to them (Luke XII).
Source: Commentary on Samuel