The believer takes comfort in knowng that whatsoever God Almighty has purposed to do, He will complete it.
An enlightened sinner knows (by faith) that before the world was spoken into existence by the Lord Jesus Christ, the Father, Son, and Spirit, entered into an eternal covenant.
In that covenant, the Father chose out of every nation, kindred, and tongue, an exact number of people that would be brought (by faith) to embrace the chosen means of salvation — the Lord Jesus Christ.
In perfect agreement with that covenant, the Eternal Son purposed to take upon Himself the form of sinful flesh, though He himself was without sin, and flawlessly work out (as a man) every point of the holy law of God, thereby acquiring a perfect righteousness that would in time be imputed (charged to the account of) every one that the Father had chosen.
The Eternal Spirit, (in perfect agreement with the Father and Son) shall, in time, quicken (make alive spiritually) every person whose name is found written in the book of life from the foundation of the world (Revelation 17:8).
Those whose names were written in the book of life are those that the Father chose, and the Son shall redeem.
There are three that bear record in heaven, the Father, the Word, and the Holy Ghost, and these three are one.
This oneness of God in purpose and will shall forever be the comfort of every sinner redeemed by grace.
By Marvin Stalnaker