Biblical Election is when God chooses or elects someone or something for a specific purpose simply because He chooses to do so, since He can do anything He wants because He is God. God's work of Salvation began with His sovereign, uninfluenced, undeserved love.(1)
An example of biblical election can be found in the Book of Romans where Paul shows us how God used election.
Yet, before the twins were born or had done anything good or bad-- in order that God's purpose in election might stand: not by works but by him who calls-- she was told, "The older will serve the younger" (Romans 9:11-12).
In other words, when Rebekah was pregnant with twins (Jacob and Esau), God chose (or elected) Jacob over Esau. It wasn't because of anything Esau or Jacob had done, they weren't even born yet. Although sometimes it may not seem fair to us on the human level, God can choose who He wants and that is one of His ways. Election is unconditional, meaning it is by God's choice. (See Genesis 25:23)
Ephesians says it this way concerning those who believe in Christ as Messiah.
For he chose us in Him before the creation of the world to be holy and blameless in his sight. In love he predestined us to be adopted as his sons through Jesus Christ, in accordance with his pleasure and will--(Ephesians 1:4-5).
This is something we will not completely understand until we get to Heaven. God, who is a sovereign God can do as He pleases. Our ways are not His ways and some things He does it is hard for us to understand why or how.
Jesus said to His disciples, “You did not choose Me, but I chose you” (John 15:16).
Another example that God's electing love is not conditioned on any merit in its recipients is found in God choosing Israel to be his "Chosen People."(1)
For you are a holy people to the Lord your God. The LORD your God has chosen you out of all the peoples on the face of the earth to be his people, his treasured possession. The Lord did not set His love on you nor choose you because you were more in number than any of the peoples, for you were the fewest of all the peoples" (Deuteronomy 7:6-7).
This question of choice is called “election” because of the Greek word for those who are chosen—the Bible calls them eklektos.
For more on this please read Israel The Chosen Nation.
The doctrine of God's sovereign, elective love has several practical benefits. It crushes human pride (Titus 3:5) since God gets all the credit for salvation. It exalts God (Ps. 115:1), as He receives praise for His love. It produces joy (1 Pet. 1:1-2, 6, 8), as believers rejoice in their salvation. It grants unimaginable privileges (Eph 1-3). It provides holiness in the lives of the elect (Col. 3:12-13), and it provides security (Phil. 1:6).(1)
"Christians are the elect, chosen by God solely by His sovereign, loving purpose, apart from any human merit or wisdom. God in eternity past sovereignly chose all believers to salvation, drawing them to Himself in time, by the work of the Holy Spirit. (John 6:37,44; Rom. 9:15-16; 1 Cor. 1:9; Eph. 1:4-6, 11; 2 Thess. 2:13; 2 Tim. 1:9 cf Acts 13:46-48; Rev. 13:8; Rev. 17:8). Jesus instructed the Disciples, "You did not choose Me, but I chose you... (John 15:16). The Father, Son, and Holy Spirit elected not only the Apostles but also all who have believed throughout history. In His High Priestly Prayer, Jesus prayed, "I ask on their behalf; I do not ask on behalf of the world, but of those whom you have given Me; for they are Yours (John 17:9)".(2)
Those whom God willed for salvation before the foundation of the world (Eph. 1:4; 2 Tim. 1:9) will in faith embrace Christ. As He declared in John 6:37 "All that the Father gives Me will come to Me, and the one who comes to Me I will certainly not cast out."(3)
1). The MacArthur New Testament Commentary on 1&2 Thessalonians p. 287.
2). The MacArthur New Testament Commentary on 1&2 Thessalonians p. 20.
3). The MacArthur New Testament Commentary on John 1-11 p.34.