One of the sovereign works of God is that of election. That is to say that God in eternity past chose some people for salvation. And this is not based on any goodness of the individual but on the grace and mercy of God. Paul Enns gives an excellent definition of election when he says:
What is election? Election may be defined as “that eternal act of God whereby He, in His sovereign good pleasure, and on account of no foreseen merit in them, chooses a certain number of men to be the recipients of special grace and of eternal salvation.” One of the principal passages concerning election is Ephesians 1:4 in the statement “He chose us.” The verb chose is the Greek eklego, which means “to call out” from among the people. The word means that God selected some individuals from out of the masses. Moreover, the word is always used in the middle voice meaning God chose for Himself. This describes the purpose of the choosing—God chose believers to be in fellowship with Him and to reflect His grace through their living a redeemed life.
The question concerning election is not whether one understands it but whether the Bible teaches it. If indeed the Bible teaches election (or any other doctrine), then one is obligated to believe it. The doctrine of election includes a number of areas: Israel is elect (Deut. 7:6); angels are elect (1 Tim. 5:21); the Levitical priests were elect (Deut. 18:5); Jeremiah the prophet was elect (Jer. 1:5); and believers are elect (Eph. 1:4).
It is imperative before we move on to answer the question why does God elect, why does he chose some? The Bible gives several answers to this important question. The first is that it for His own good pleasure (Ephesians 1:5), Paul explains that the reason God predestines us was… “according to the good pleasure of his will”. The second reason we see from the Bible as to why God elects is so as to display his glory (Isaiah 43:7)
The other reason as to why God elects is His foreknowledge Romans 8:29 says: For whom he did foreknow, he also did predestine to be conformed to the image of his Son that he might be the firstborn among many brethren.
What is the point of all this you ask? God does what He pleases, when he pleases, how he pleases and to whom he pleases. He has the right and power to do what he pleases for his own glory! Hence God chose to elect some to salvation. He planned salvation Therefore when the second member of the God- Jesus Christ came on earth to die for sinners and pay the penalty of sin. He came to carry out the work of salvation.
The work of salvation that God the father had planned. That is that those whom he chose (election) should come to salvation. This is what Christ is talking about in His priestly prayer in John 17. Several times in the chapter he says God has given him a group of people and has done all the work i.e. given them eternal life (v3), taught them the truth (v 6) etc. The logical flow is obvious God the father chose some for salvation and planned the work of salvation. God the son came to die for those whom the father chose and carried out the work of salvation. John Piper summarizes this point quit well in his book Does God desire all men to be saved when he says:
Christ's atonement is not performed in abstraction, but is performed in accordance with the purpose of the Father and is performed in relation to specific people whom God has purposed to be saved. Like Paul, each Christian is brought to the amazing realization that the Son of God... loved me, and delivered Himself up for me. (Gal 2:20) It is by saving particular sinners that God saves the world. By sovereign grace, the Lord makes Himself our God and we come to know Him personally, intimately, particularly.
This then leads us to the third person of the Godhead and His role in the plan of salvation. The Holy Spirit through the word of God convicts and regenerates the elect to salvation. He is the one who draws men and seals them and God gives him as a seal or pledge of our salvation. William Evans makes this same point when he says:
The Holy Spirit is the one who seals the work of salvation and completes the work of salvation in the elect. The Holy Spirit seals, attests, and confirms the work of grace in the soul by producing the fruits of righteousness therein. It is the Spirit of life in Christ Jesus who gives us freedom from the law of sin and death (Rom. 8:2). He is called the Holy Spirit, not only because He is absolutely holy Himself, but also because he produces that quality of soul-character in the believer. The Spirit is the executive of the God-head for this very purpose. It is the Spirit's work to war against the lusts of the flesh and enable us to bring forth fruit unto holiness (Gal. 5:17-22).
We have established that God is sovereign and in his sovereign wisdom he elects some people to salvation for his own good pleasure and for his own glory. We have further established that salvation is the work of the triune God. The father planned, the son carries out and accomplishes the plan of salvation and the Holy Spirit seals and implements the plan of salvation. David and Paul Gibson writing in the great work “From He came and sought her” explain that:
The doctrine of definite atonement states that, in the death of Jesus Christ, the triune God intended to achieve the redemption of every person given to the Son by the Father in eternity past, and to apply the accomplishments of his sacrifice to each of them by the Spirit. The death of Christ was intended to win the salvation of God’s people alone.