The serpent had said that mankind would become like God. Here we see that the father of lies is a master manipulator. Rather than lie outright, he corrupts half-truths. Adam and Eve indeed did not immediately die when they ate the fruit. At least not physically. And now we discover that, in one sense, they have become like heavenly beings. They now know about good and evil, having experienced both. They are no longer innocent. And what a loss!
God continues to show mercy and to reveal that He has a plan to reconcile things to the way He planned for them to be. In an unusual literary move the author records a partial declaration of God. Or, perhaps, God Himself left things dramatically unsaid. “…now, lest he reach out and take from the tree of life as well and live forever…” What is left unsaid here? Is it merely “let us drive him out,” or something even more terrifying? What would be the result of immortality and sin? Some think life as it is today is hellish, but that would be a literal hell. Separation from the Creator for eternity, with no possibility of redemption.
As it stands, death is mercy. God drives the couple from the garden. (Drives, not sends. How terrifying must that have been?) So no mankind has no access to immortality. Death is a result of sin because we have been driven away from access to immortality, but that also gives God the opportunity to set up a substitutionary death in our place. The punishment can be paid by an innocent and applied to those who will receive it.
God’s great plan has been set in motion.