We know Adam & Eve would only die both spiritually and eventually physically if they disobeyed Almighty God. Gen 2:17 "but of the tree of the knowledge of good and evil you shall not eat, for in the day that you eat of it you shall surely die.”
This was the only condition indicated in which they would die. In other words, by implication if they did not eat from that tree they would continue living or having life that lasted forever, living forever. But what then was the purpose of the "tree of life", Gen 2:9 "And out of the ground the LORD God made to spring up every tree that is pleasant to the sight and good for food. The tree of life was in the midst of the garden, and the tree of the knowledge of good and evil"
Well when Adam and Eve did disobey their Creator what happened? Gen 3:22-24 Then the LORD God said, “Behold, the man has become like one of us in knowing good and evil. Now, lest he reach out his hand and take also of the tree of life and eat, and live forever-” therefore the LORD God sent him out from the garden of Eden to work the ground from which he was taken. He drove out the man, and at the east of the garden of Eden he placed the cherubim and a flaming sword that turned every way to guard the way to the tree of life.
Did you notice the words “lest he reach out his hand and take also of the tree of life and eat, and live forever”? So, eating of the tree of life meant being able to “continue living” or live forever. But hold on you say! God drove them out so they could not eat of the tree! Yes, so they therefore would eventually die physically as recorded in scripture.
We are not going to go into the “in the day that you eat of it you shall surely die” aspect of what is a day in Gods eyes at this time. I do not see the tree of life having been put there just for show and with no purpose by God. He is the God of purpose. It certainly was not put there by God for Adam and Eve or their offspring to partake of after they sinned so that they could keep living as it shown above by it being protected from such partaking of by God using the Cherubs as guards. It also did not just stand there as a symbol to everlasting life but was to be partaken of at some point to maintain their everlasting life as will be shown by considering Revelation.
Yes, Revelation is where the tree of life again appears in the “paradise of God”. Rev 2:7 He that has an ear, let him hear what the Spirit said to the churches; To him that overcomes will I give to eat of the tree of life, which is in the middle of the paradise of God. – AKJV
Remember eating of that tree would grant continuous life (Gen 3:22) and here the same is applied to those who “overcome” or conquer at that time over their sinful life and all its tribulation and remain faithful to God and Christ Jesus. They would gain access to the tree of life and waters of life in the city of God, New Jerusalem.
Rev 22:2 through the middle of the street of the city; also, on either side of the river, the tree of life with its twelve kinds of fruit, yielding its fruit each month. The leaves of the tree were for the healing of the nations.
Rev 22:14 Blessed are those who wash their robes, so that they may have the right to the tree of life and that they may enter the city by the gates.
But just as in Adam and Eve’s time there will be those who are prohibited from access to the holy city and to the tree of life.
Rev 21:27 But nothing unclean will ever enter it, nor anyone who does what is detestable or false, but only those who are written in the Lamb's book of life. “enter it” – “it” being the holy city New Jerusalem ref. prev. verses
Rev 22:15 Outside are the dogs and sorcerers and the sexually immoral and murderers and idolaters, and everyone who loves and practices falsehood.
Rev 22:19 and if anyone takes away from the words of the book of this prophecy, God will take away his share in the tree of life and in the holy city, which are described in this book.
The scriptures state that those who are granted access to the tree of life will keep living while those who are not permitted to eat from the tree will likely die like Adam and Eve did. Yes that does mean man will continue to have to be obedient in order to keep living as they will not be incorruptible or immortal like God, Jesus and those whole rule with Christ. They will after all still be physical earthly human creatures like Adam and Eve were before they sinned. Adam and Eve were sinless, that is until they sinned and passed that weakness on. Otherwise, one would be saying that humans would become immortal and unable to ever do what is wrong and therefore incorruptible.
I believe humans who prove themselves worthy will return to what Adam and Eve lost where they can live forever and never die under the care of Almighty God and Jesus just as it was meant to be. I cannot find anywhere in scripture where is says humans will never sin again. Rather the contrary.
According to Revelations and even these very familiar verses in Isaiah:
Isa 65:17-25 “For behold, I create new heavens and a new earth, and the former things shall not be remembered or come into mind. But be glad and rejoice forever in that which I create; for behold, I create Jerusalem to be a joy, and her people to be a gladness. I will rejoice in Jerusalem and be glad in my people; no more shall be heard in it the sound of weeping and the cry of distress. No more shall there be in it an infant who lives but a few days, or an old man who does not fill out his days, for the young man shall die a hundred years old, and the sinner a hundred years old shall be accursed. They shall build houses and inhabit them; they shall plant vineyards and eat their fruit. They shall not build and another inhabit; they shall not plant and another eat; for like the days of a tree shall the days of my people be, and my chosen shall long enjoy the work of their hands. They shall not labor in vain or bear children for calamity, for they shall be the offspring of the blessed of the LORD, and their descendants with them. Before they call I will answer; while they are yet speaking I will hear. The wolf and the lamb shall graze together; the lion shall eat straw like the ox, and dust shall be the serpent's food. They shall not hurt or destroy in all my holy mountain,” says the LORD.