Now the fact that the great majority of living things never do die naturally but for the most part come to an end by accident, indicates two rather obvious but very important circumstances regarding the nature of life in such organisms. But, secondly, they do not need to die, for they can actually go on living indefinitely. We thus have an important distinction to note regarding the meaning of the term physical immortality as applied to any organism including Adam and Eve as created. In the light of modern research, physical immortality means that a living creature will not die unless it is killed. It does not mean that it cannot be put to death but only that death is not an inherent condition of its life.
Death overtakes it, happens to it.
By avoiding accident successfully, it is quite capable of living on for ever. And this, I believe, was precisely the position of man when he was first created. And physical immortality in such a state would have been condemnation to everlasting defeat and disappointment from which there could be virtually no escape except by some kind of suicide. It is almost certain that it was for this reason, God drove the man out of the Garden and excluded him rigidly from the Tree of Life. From this graphic record of the events that transpired in Eden, events that seem almost childishly naive, arose a situation for mankind which called forth the working out of a plan of redemption made possible only because the laws of nature had been designed to accommodate it.