The tree of life was planted in the middle of the Garden of Eden (Genesis 2:9). It supplied what was necessary for Adam's life to continue. When Adam sinned, he lost access to the tree of life so that he would not live forever (Genesis 3:22-24).
This tree of life is mentioned several times in the book of Proverbs. The first time is in 3:18. The context beginning in verse 13 is speaking of wisdom and the great benefit of finding wisdom. Also in 11:30 the result of righteousness is the tree of life. Desire fulfilled is called a tree of life in 13:12, as is a soothing tongue in 15:4.
The book of Revelation gives us a broader understanding of the tree of life. Revelation 2:7, “To him who overcomes, I will grant to eat of the tree of life…” Eating of this tree of life is the reward for the overcomers. The Apostle Peter wrote in 2 Peter 1:4 (NASB), “He (God) has granted to us His precious and magnificent promises, so that by them you may become partakers of the divine nature, having escaped the corruption that is in the world by lust.” Thus, overcoming Christians will receive the divine nature as a reward for faithfulness.
Mankind will once again have the opportunity to eat of the tree of life when Jesus and his Bride reign on earth. Revelation 22:1-2 (NASB), “…a river of the water of life…coming from the throne of God and of the Lamb…On either side of the river was the tree of life, bearing twelve kinds of fruit, yielding its fruit every month; and the leaves of the tree were for the healing of the nations.” What gives life in God’s kingdom?
Jesus is identified as mankind’s father or life-giver in Isaiah and 1 Corinthians. Isaiah 9:6 reads, “For unto us a child is born, unto us a son is given: and the government shall be upon his shoulder: and his name shall be called Wonderful, Counsellor, The mighty God, The everlasting Father, The Prince of Peace.” 1 Corinthians 15:45 (NASB) teaches, “The first man, Adam, became a living soul. The last Adam became a life-giving spirit.”
When Christ (Head and body) establish God’s kingdom on earth, resurrected mankind will be healed of their sin-sickness; physically, mentally and spiritually. Thus, in symbol, Christ becomes the tree of life and offers eternal life on earth to those obedient to God’s perfect, loving will. Revelation 22:14(NASB), “Blessed are they that do his commandments, that they may have right to the tree of life, and may enter in through the gates into the city.” The disobedient will not have access to the tree of life and will therefore cease to exist (die) as shown in verse 15.