HOW IS IT POSSIBLE TO LIVE FOREVER?

(The following is from Chapter 12 of the Book of Alma.  Dr. Robert J. Matthews, former Dean of Religious Education at BYU explains after reading the verses):

20. But there was one Antionah, who was a chief ruler among them, came forth and said unto him: What is this that thou hast said, that man should rise from the dead and be changed from this mortal to an immortal state, that the soul can never die?

21. What does the scripture mean, which saith that God placed cherubim and a flaming sword on the east of the garden of Eden, lest our first parents should enter and partake of the fruit of the tree of life, and live forever? And thus we see that there was no possible chance that they should live forever.  "(Then Alma says I was just about to explain this, then skipping to verse 24)":

24. And we see that death comes upon mankind, yea, the death which has been spoken of by Amulek, which is the temporal death; "(Now that comes upon all mankind because of the fall of Adam)" nevertheless there was a space granted unto man in which he might repent; therefore this life became a probationary state; a time to prepare to meet God; a time to prepare for that endless state which has been spoken of by us, which is after the resurrection of the dead.

25. Now, if it had not been for the plan of redemption, which was laid from the foundation of the world, there could have been no resurrection of the dead; but there was a plan of redemption laid, which shall bring to pass the resurrection of the dead, of which has been spoken.

26. And now behold, if it were possible that our first parents could have gone forth and partaken of the tree of life "(immediately, is the point being made)" they would have been forever miserable, having no preparatory state; and thus the plan of redemption would have been frustrated, and the word of God would have been void, taking none effect.

"In other words, they would have lived forever in their sins.  So a space of time was granted that man might repent, so that when he does partake of the tree of life, he will be washed clean rather than living forever in his sins.  That's the point he's making there. When he says life becomes a probationary state.  The problem with Adam and Eve taking of the tree of life immediately is that they would not have had a space of time to repent."  (Round Table Discussion on the Book of Mormon with Robert J. Matthews, Mont Nyman and Todd Parker on BYU TV).