Earlier, God had informed Adam and Eve that sin exacts a penalty, death - the cessation of life - and, if a person will not repent of sin, this means total death - no chance for eternal life. This threat God has held over mankind's head from the beginning. Notice, however, how the Devil replies:
Then the serpent said to the woman, "You will not surely die. For God knows that in the day you eat of it your eyes will be opened, and you will be like God, knowing good and evil." (verses 4-5)
Here is the lie: "Look, Adam and Eve, you have an immortal soul. God cannot enforce His threat." In its various forms through the centuries, this doctrine of man having eternal life already has appeared time and again.
In theological terms, this belief is the basis of the "Doctrine of Eternal Security." What is worse, this heretical doctrine has resurfaced in the church, having been part of the latest apostasy. It cannot stand, however, before the light of God's Word. God has a far superior way of dealing with humanity - both righteous and incorrigible.
Richard T. Ritenbaugh
Do We Have 'Eternal Security'?