Eternal life, in biblical usage, is more than endless existence. Zoe, the noun to which the adjective aionios is attached in John 12, is the spiritual vitality of God, life lived the way God lives it. This distinguishes it from immortality, which Paul separates from eternal life in Romans 2:7. The Greek gods were immortal but lacked eternal life, since immortality speaks only of duration and not quality. John 17:3 defines eternal life as knowing the only true God and Jesus Christ. This is ginosko, the same word used for intimate relationship, and it means knowing God, not merely knowing about Him. Such knowledge gives power to live with quality, as Hosea 4:6, Proverbs 3, and Isaiah 11:9 show. Eternal life is received now. Believers have already passed from death to life (John 5:24; Ephesians 2:1), entering a dimension of life that the unconverted cannot perceive. John 12:24-26 gives the core principle: life bears fruit only when sacrificed, and psuche (physical life) must be given up for zoe. Imitating Christ means living to give rather than to get, as God does. First John shows that eternal life was manifested in Christ and includes present fellowship with the Father and Son, expressed in keeping the commandments and doing God's will. At the end of life, each person receives the kind of life he has been living.

Biblical eternal life (zoe) is more than endless existence. It is the quality of life God Himself lives, which is why Paul distinguishes it from immortality in Romans 2:5-7. The Greek gods had immortality without it, since immortality says nothing about the character of a life. John uses psuche for physical life, but zoe, usually joined to "eternal," for the spiritual vitality of God. Jesus defines it in John 17:3 as knowing the Father and the Son. That knowing (yada', ginosko) is not merely intellectual but an intimate, personal relationship, so eternal life is already possessed in principle at conversion, when a person passes from death to life (John 5:24; Ephesians 2:1). Lexical and commentary support (Zodhiates, Barclay) confirms that it refers primarily to quality, not duration. Knowing God brings power and abundance, while ignorance of Him destroys (Hosea 4:6; Proverbs 3). Living this life means living as God does, by giving rather than getting. John 12:24-26 shows the way: like a seed that must die to bear fruit, one must sacrifice self-centeredness in service to God and others. In 1 John 1:1-4 this life was manifested in Christ and can be fellowshipped with now, a fellowship marked by self-sacrificial love within the church. Doing God's will, keeping His commandments, and overcoming sin prepare a person to walk with Him forever, while those out of harmony with His will cease to exist.

John uses zoe (life) thirty-six times, three times more than Matthew, Mark, and Luke combined, and the word almost opens and closes the book (John 1:4; 20:31). By itself it means vitality or activity, the opposite of death, and the Bible applies it even to plant and animal life. John adds two connotations. First, it is the opposite of destruction, condemnation, and death (John 3:16; 5:24, 29), which presents Jesus as the fountainhead of life, so anyone wanting life must go to Him as one goes to a spring or well. Second, it carries a sense of quality. Without Christ a person merely exists; with Him he has God-life, the abundant life of John 10:10. John shows this life by the example of how Jesus lived, not by lists of do's and don'ts. It is filled with love, joy, peace, patience, and self-control, and it is the only kind of life worth living for eternity. Eternal life without this way of living would be a curse rather than a gift, which is why God demands change now. Freedom from the fear of death, as in Jesus' handling of Lazarus's death, is an example of this quality. The life of Christ also functions as light, revealing flaws and true standards and guiding those who believe.

Zoe, the Greek noun for life, appears 134 times in the New Testament, first in Matthew 7:14. In Colossians 3:3, Paul says, "You have died, and your life is hidden with Christ in God." The life he means is not biological, since a person who dies physically has no life, hidden or otherwise. It is the new life that begins when the old man dies in baptism. The Greek present perfect shows that this life exists now and does not wait for the first resurrection. Many paraphrases add "new" or "real" before "life," though neither adjective is in the Greek, and the Jerusalem Bible stresses the present sense by rendering zoe as "now the life you have." Romans 6:4 describes the same life as rising from the water to newness of life. Christians therefore enjoy this life now. Biological death may interrupt it, but those alive at Christ's return will continue in it without interruption, simply changed from mortal to immortal. Its continuation after the first resurrection is eternal life as defined in John 17:3.

In Revelation 20, the Book of Life is named with the Greek words biblion zoe (975 and 2222), literally "book life," which parallels the Hebrew sepher and chay of Psalm 69:27-28, a book, register, or scroll of living things. This registry belongs to God, who recorded every thought and action of every person who has lived, and He will use it in His final judgment to determine who attains eternal life and who suffers eternal death. Those receiving eternal life have their names entered in it, while anyone not found written there is cast into the lake of Fire. Though some scholars distinguish a Book of Life from a Book of the Living, the two share the same purpose and function. John saw it opened in vision, and because Christ told him to write what he saw, it should be understood as a literal book, even if it also broadly represents God's will and judgment. It exists for the benefit of His children, not to aid His memory, and it reveals Him as a God of order who keeps meticulous records. A name is entered by overcoming one's sinful nature, as Christ tells each of the seven churches. Yet there is no eternal security: God will blot out the name of anyone who turns from commitment to Him (Revelation 3:5; 22:19; Exodus 32:33).