God at Genesis 2:17 warned Adam 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.” It would seem that when Adam passed that warning on to Eve, she took it very seriously because she expanded on and emphasized the warning when speaking with the serpent. The woman said to the serpent, God said, ‘You shall not eat of the fruit of the tree that is in the midst of the garden, neither shall you touch it, lest you die.’” (Gen 3:3) You will notice that she added, “neither shall you touch it.” “But the serpent said to the woman, “‘You will not surely die.’” (Gen 3:4) Was the serpent (i.e., Satan), telling the truth, as Adam would go on to live for another 930-years? (Gen. 5:5) No, Satan lied! In the day of their eating the fruit of the forbidden tree, they died spiritually.
If we look at the context of Adam when he received the command at Genesis 2:17, how would have Adam understood the expression, “in the day that you eat of it”? It is true, that Moses said to God, “For a thousand years in your sight are but as yesterday.” (Ps 90:4) In addition, while addressing the extent of Jehovah God’s patience, the apostle Peter said, “that with the Lord one day is as a thousand years and a thousand years as one day.” (2 Pet 3:8) However, Adam lived and died long before both of these statements, and would have had no knowledge of such. It was not as though Adam was thinking of his great love for Eve, and saying to himself, “If I eat of the forbidden tree, I will have one of Jehovah’s days to live, a thousand years to spend with Eve. Yes, Adam would have no knowledge with which to reason in such a way. In other words, he would have understood the word “day” to be a literal twenty-four-hour day. God does not speak ambiguously, and he would have expressed himself in order to be understood, according to what Adam would know as to the terms that were used. Thus, God meant exactly what Adam would have understood it to mean, a twenty-four-hour day. God did not mean, “the tree of the knowledge of good and evil you shall not eat, for in the [thousand-year-long day] that you eat of it you shall surely die.” Such a statement as that would have had no force in the mind of Adam; it would have lost all intended force of Jehovah’s warning.
Adam would have received the Genesis 2:17 warning directly from God, even if a representative, his only-begotten Son, “the Word”, delivered that warning. This, of course, begs the question, why then did Adam and Eve not die ‘in a twenty-four-hour day?’ Well, we must ask another question first. As to the Bible, what is death? The World Book Encyclopedia (1987, Vol. 5, p. 52b) pointed out: “A person whose heart and lungs stop working may be considered clinically dead, but somatic death may not yet have occurred. The individual cells of the body continue to live for several minutes. The person may be revived if the heart and lungs start working again and give the cells the oxygen they need. After about three minutes, the brain cells, which are most sensitive to a lack of oxygen, begin to die. The person is soon dead beyond any possibility of revival. Gradually, other cells of the body also die. The last ones to perish are the bone, hair, and skin cells, which may continue to grow for several hours.” We know that the breathing and the active life force (Heb., ruach chaiyim) maintained in the cells by the blood are very important. From this, we can see that it is not the termination of breathing and the heartbeat alone, but also includes the loss of the life force from the body’s cells that brings the sort of physical death as spoken of in the Scriptures. Ps 104:29; 146:4; Eccl 8:8.
However, the Scriptures speak of another kind of death, a spiritual death, which is illustrated by the death spoken of above as the condition of humankind at present but is also relative to our discussion as well. In other words, Adam died spiritually on the very day of eating from the forbidden tree, and this would result in old age and eventually death. A man was begging off from following Jesus, saying, “Lord, let me first go and bury my father.” Jesus responded, “Leave the dead to bury their own dead. . .” (Lu 9:59-60) The man’s father was not dead yet, the son simply wanted to hold off following Jesus until his father died, and was simply looking for a way out. However, Jesus’ response, “Leave the dead to bury their own dead,” illustrated that spiritually dead and being dead are, in essence, one and the same unless there is some sort of intervention (more on that later) because physical death is the eventuality of those that are spiritually dead.
In addition, we have the apostle Paul referring to the woman living for sensual indulgence as “dead even while she lives.” (Lu 9:60; 1Ti 5:6; Eph 2:1) Physical death was the sentence handed down to Adam and thus his descendants as well. However, this was brought about by way of the spiritual death, which affected Adam and Eve the very moment they ate from the forbidden tree. They were now alienated from God, and removed from the symbolic tree of life, being sent out from the Garden of Eden. This alienation is self-evident as the two vainly tried to hide from God, their guilt ridden conscious affecting them. (Gen 3:8) The apostle Paul expressed it as being “dead in the trespasses and sins,” becoming “children of wrath.” (Eph. 2:1–3)
Romans 6:7 says, “one who has died has been set free from sin.” However, Roman 6:2, 11 informs us that a Christian can ‘consider themselves dead to sin and alive to God in Christ Jesus.” Romans 7:2-6 helps us to appreciate that Christians “are released from the law, having died to that which held us captive, so that we serve in the new way of the Spirit and not in the old way of the written code. Jesus said that he came to earth “to give his life as a ransom for many.” (Matthew 20:28).
Adam and Eve were guilty before God and then stood before him in an unrighteous condition. Within this unrighteous condition came a defilement and pollution of a new state of being, fallen flesh (Gr., sarx), which placed Adam and his descendants in an alienated position toward God and in enmity toward him (Rom 8:5-8) Hence, the mindset of imperfect man is mentally bent and geared toward evil. Because of Adam, we are born into sin (missing the mark of perfection) and are looking at the sentence of death. (Ps 51:5; Rom 5:12; Eph 2:3). This was the condition of Adam and Eve, the very moment they willfully chose to rebel against God, and commit that awful transgression. Instantly, they were thrown into the condition of a spiritual death. At that moment there was no hope for the human race, regardless of what any would do in life, the sentence would be death. However, Jehovah is a God of mercy, and while the human race merited death, we received undeserved kindness, which can be found in Genesis 3:15.
As has been stated and is obvious from Scripture, the physical death did not come immediately. God had created them perfectly after all; therefore, they would take far longer to grow older and die. Regardless, they were no longer going to be perfect but had taken on imperfection. God had removed his blessing of them as being good, and, eventually, their imperfection would show signs of growing old and impending death
The penalty was unavoidable. As to justice, from the viewpoint of God, Adam and Eve died that day. (Compare Luke 20:37-38.) However, to fulfill his own will and purpose regarding the inhabiting of the earth, Jehovah permitted them to produce a family before they were to grow old, get sick and die. All the same, while Adam and Eve may not have been aware of God’s viewpoint of time, they both did die within one of his days, a thousand years. While there may be no absolute connection between Moses or Peter’s statement about the way God views time, it seems a bit too much, to be a mere coincidence that Adam lived to be 930-years, and Methuselah lived to be 969-years, with not one preflood person living beyond a thousand years old.―Genesis 5:3-5; Psalm 90:4; 2 Peter 3:8.
 See question on Genesis 3:8 as to who had spoken directly with Adam.