What did "death" mean in the Garden of Eden?

In order to fully understand the Biblical meanings of death, we must examine the two different deaths the Bible speaks of. First, our physical body will cease to exist at some point and when it stops functioning, we refer to this as death. Secondly, the Bible speaks about a spiritual death, which is a state of existence in which our physical body is still alive, but our spirit is corrupted by a sin nature. In Ephesians 2 Paul reminds believers that we were dead prior to God showing grace to us and producing faith in us; we were all dead in sin because of the fall.

EPH. 2:1 And you were dead in your trespasses and sins, 
EPH. 2:2 in which you formerly walked according to the course of this world, according to the prince of the power of the air, of the spirit that is now working in the sons of disobedience. 
EPH. 2:3 Among them we too all formerly lived in the lusts of our flesh, indulging the desires of the flesh and of the mind, and were by nature children of wrath, even as the rest. 

Spiritual death is characterized by a separation from God, an inability to know God or to fellowship with Him. Man alone has complete inability to seek God on his own initiative as we see in Romans 3.  

ROM. 3:10 as it is written:
“There is no righteous person, not even one;
ROM. 3:11 There is no one who understands,
There is no one who seeks out God;
ROM. 3:12 They have all turned aside, together they have become corrupt;
There is no one who does good,
There is not even one.”
ROM. 3:13 “Their throat is an open grave,
With their tongues they keep deceiving,”
“The venom of asps is under their lips”;
ROM. 3:14 “Their mouth is full of cursing and bitterness”;
ROM. 3:15 “Their feet are swift to shed blood,
ROM. 3:16 Destruction and misery are in their paths,
ROM. 3:17 And they have not known the way of peace.”
ROM. 3:18 “There is no fear of God before their eyes.”
ROM. 3:19 Now we know that whatever the Law says, it speaks to those who are under the Law, so that every mouth may be closed and all the world may become accountable to God; 
ROM. 3:20 because by the works of the Law none of mankind will be justified in His sight; for through the Law comes knowledge of sin.

When God promised Adam that on the day he ate of the tree, he would surely die, we must conclude that the death was a spiritual death, which exhibits separation from a Holy God, since Adam’s physical body lived to be 930 years old.

GEN. 5:5 So all the days that Adam lived were 930 years, and he died.

The nature of a Holy God by definition must follow through with the consequence of Genesis 2:17 which mandates a death, specifically a spiritual death. Adam failed to believe in God’s promise, thus resulting in spiritual separation from God. By this one sinful choice, he brought the rest of mankind down with him. All who come into the world bear the marks of Adam and Woman’s sinful choice, resulting in a world filled with sin and disobedience.

However, further in Genesis we see that God did not leave Adam and Woman in this state:

GEN. 3:15 And I will put enmity
Between you and the woman, 
And between your seed and her seed; 
He shall bruise you on the head, 
And you shall bruise him on the heel.” 

Genesis 3:15 is referred to as the first gospel of the Bible because these words spoken by God contain the first promise of redemption. Jesus Christ is the preeminent seed of woman who will one day come to crush the serpent’s head with a lethal blow. However, in the process of Jesus’ victory, His heel would be bruised, which isn’t lethal, by His temporary death on the cross. This most important verse anticipates that the seed of woman, Jesus Christ, would win the victory over Satan’s rebellion toward God.

God’s promise in Genesis 3:15 of woman’s seed being the One to destroy the works of the devil points to the person of Jesus Christ one day entering creation himself to correct the problem of Adam’s disobedience. 

Why is this promise of old so important to Adam and his spiritual state?

GEN. 3:20 Now the man called his wife’s name Eve, because she was the mother of all the living. 
GEN. 3:21 The LORD God made garments of skin for Adam and his wife, and clothed them. 

In the midst of such a shameful and monumental change within the very soul of man and Woman, Adam takes this time to rename his wife from Woman to Eve. But why this pivotal change in Adam’s desire for woman? The word Eve is chavvay in Hebrew – meaning life or living.

Adam has just witnessed God declare that He would bring a solution to the sin problem through a seed that Woman would provide without man. The seed is the solution that would result in the destruction of the serpent. 

This specific seed of Woman speaks to the virgin birth of Jesus Christ, the atonement for all mankind. In the very name change of woman, Adam is showing proof that he received this word from God and believed it. In this moment Adam becomes a believer through showing faith in God’s word or promise. 

In response to their belief in God’s promise, God then demonstrates forgiveness towards them by making Adam and Eve animal skins for clothing. God is the one that provides the animal skins through the work of his own hands. This sacrifice by God provided a sufficient covering for man’s sin and shame, whereas previously man tried to cover himself by his own work in making leaf coverings which were insufficient. It is important to note that this death is the first physical death ever recorded in creation. Innocent blood was shed by God himself to cover mankind’s sin. 

You may find the following articles on our website helpful for further study:

Soul vs. Spirit?
Will all believers experience a spiritual and physical death?

Moreover, you may find our Genesis teaching expand on the details of this account.

Scripture quotations taken from the (NASB®) New American Standard Bible®, Copyright © 1995, 2020 by The Lockman Foundation. Used by permission. All rights reserved. www.lockman.org