The covenant of redemption is the theological term for the agreement that was made between the God the Father, God the Son, and God the Holy Spirit in how they were going to redeem for themselves the elect. This covenant is not mentioned by name in scripture but it is clearly implied that an agreement had been made between the Godhead. Much like the term Trinity does not appear in scripture but the concept is clearly seen. Here is a quote by Charles Hodge explaining where this idea can be seen in scripture…
“In Psalm 40, expounded by the Apostle as referring to the Messiah, it is said, “Lo, I come: in the volume of the book it is written of me, I delight to do thy will,” i.e., to execute thy purpose, to carry out thy plan. “By the which will,” says the Apostle (Heb.10.10), ”we are sanctified through the offering of the body of Jesus Christ once for all.” Christ came, therefore, in execution of a purpose of God, to fulfil a work which had been assigned Him. He, therefore, in John 17.4, says, “I have finished the work which thou gavest me to do.” This was said at the close of his earthly course. At its beginning, when yet a child, He said to his parents, ” Wist ye not that I must be about my Father’s business?” (Luke 2.49.) Our lord speaks of Himself, and is spoken of as sent into the world. He says that as the Father had sent Him into the world, even so had He sent his disciples into the world. (John 17.18). “When the fulness of the time was come, God sent forth his Son, made of a woman.” (Gal. 4.4). “God sent his only begotten Son into the world.” (1 John 4.9). God “sent his Son to be the propitiation for our sins.” (Verse 10.) -Charles Hodge-
Below is a transcript from a Spurgeon sermon where he describes this covenant and then wonders what it would have been like to be to hear this covenant being made.
“Now, in this covenant of grace, we must first of all observe the high contracting parties between whom it was made. The covenant of grace was made before the foundation of the world between God the Father, and God the Son; or to put it in a yet more scriptural light, it was made mutually between the three divine persons of the adorable Trinity.”
“I cannot tell you it in the glorious celestial tongue in which it was written: I am fain to bring it down to the speech which suits the ear of flesh, and to the heart of the mortal. Thus, I say, run the covenant, in ones like these:”
“I, the Most High Jehovah, do hereby give unto my only begotten and well-beloved Son, a people, countless beyond the number of stars, who shall be by him washed from sin, by him preserved, and kept, and led, and by him, at last, presented before my throne, without spot, or wrinkle, or any such thing. I covenant by oath, and swear by myself, because I can swear by no greater, that these whom I now give to Christ shall be for ever the objects of my eternal love. Them I will forgive through the merit of the blood. To these will I give a perfect righteousness; these will I adopt and make my sons and daughters, and these shall reign with me through Christ eternally.” Thus run that glorious side of the covenant. The Holy Spirit also, as one of the high contracting parties on this side of the covenant, gave his declaration, “I hereby covenant,” saith he, “that all whom the Father giveth to the Son, I will in due time quicken. I will show them their need of redemption; I will cut off from them all groundless hope, and destroy their refuges of lies. I will bring them to the blood of sprinkling; I will give them faith whereby this blood shall be applied to them, I will work in them every grace; I will keep their faith alive; I will cleanse them and drive out all depravity from them, and they shall be presented at last spotless and faultless.” This was the one side of the covenant, which is at this very day being fulfilled and scrupulously kept. As for the other side of the covenant this was the part of it, engaged and covenanted by Christ. He thus declared, and covenanted with his Father: “My Father, on my part I covenant that in the fullness of time I will become man. I will take upon myself the form and nature of the fallen race. I will live in their wretched world, and for my people I will keep the law perfectly. I will work out a spotless righteousness, which shall be acceptable to the demands of thy just and holy law. In due time I will bear the sins of all my people. Thou shalt exact their debts on me; the chastisement of their peace I will endure, and by my stripes they shall be healed. My Father, I covenant and promise that I will be obedient unto death, even the death of the cross. I will magnify thy law, and make it honourable. I will suffer all they ought to have suffered. I will endure the curse of thy law, and all the vials of thy wrath shall be emptied and spent upon my head. I will then rise again; I will ascend into heaven; I will intercede for them at thy right hand; and I will make myself responsible for every one of them, that not one of those whom thou hast given me shall ever be lost, but I will bring all my sheep of whom, by thy blood, thou hast constituted me the shepherd—I will bring every one safe to thee at last.”
Imagine, that for all who believe, our names were written in the Lamb’s book of life since before the foundations of the world. The Triune God has covenanted to save us, and who can stay His hand. This is eternal security.