Alma 12:21-27

21What 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.

22Now Alma said unto him: This is the thing which I was about to explain. Now we see that Adam did fall by the partaking of the forbidden fruit, according to the word of God; and thus we see, that by his fall, all mankind became a lost and fallen people.

23And now behold, I say unto you that if it had been possible for Adam to have partaken of the fruit of the tree of life at that time, there would have been no death, and the word would have been void, making God a liar, for he said: If thou eat thou shalt surely die.

24And we see that death comes upon mankind, yea, the death which has been spoken of by Amulek, which is the temporal death; 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.

25Now, 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.

26And now behold, if it were possible that our first parents could have gone forth and partaken of the tree of life 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.

27But behold, it was not so; but it was appointed unto men that they must die; and after death, they must come to judgment, even that same judgment of which we have spoken, which is the end.