"Adam was on probation.
He did disobey, and was driven from the garden. And now, said God, “lest he put forth his hand, and take also of the tree of life, and eat, and live forever;” (Gen. 3:22) - therefore the cherubim and flaming sword were placed to exclude thereafter his approach to the life giving tree.
Quite the reverse of an unconditional immortality is certainly brought to view here.
Adam could bequeath to his posterity no higher nature than lie himself possessed. The stream that, commencing just outside the garden of Eden, has flowed down through the lapse of six thousand years, has certainly never risen higher than the fountainhead; and we may be sure we possess no superior endowments, in this respect, to those of Adam." Uriah Smith