In Romans 5:12 we learn that Adam’s descendants inherit both a sinful nature as well as sin’s penalty, Death. “… Just as through one man sin entered the world, and death through sin, and so death spread to all men, because all sinned …”
What type of death did Paul mean when he wrote the book of Romans? The Bible actually has a broader view of Death than we do, and in every respect considers it as separation from God. But there are actually three aspects to the singular concept of biblical Death to consider: 1) physical death, 2) spiritual death, and 3) eternal death.
In one sense, Adam began physical death the very moment he sinned against God. Even though he would continue to function biologically for many years to come, the moment Adam disobeyed the Lord the principles of decay and corruption would begin to operate in his body. He would eventually go back to the dust from which he was formed (Gen. 2:19; Gen. 5:5).
Adam also encountered a spiritual death the moment he sinned as well. As a result of his disobedience, Adam no longer enjoyed the same intimacy with His Creator he once did. Sin had become a barrier to the special relationship between God and man. Notice that after Adam and Eve sinned they tried to hide from God’s presence when they heard Him in the garden (Gen. 3:8); the thought of avoiding the presence of God would have been inconceivable to Adam prior to sin entering his life.
Statements in the Bible teach explicitly that any descendant of Adam who is apart from Christ is dead in trespasses and sins (Eph 2:1; 2:5). As a result of Adam’s fall, his descendants’ sensibility to spiritual matters and the ability to act and respond toward God or to do good things with pure motives, are wholly absent or otherwise severely impaired (1 Cor. 2:14; Jer. 13:23; Ps. 51:5; Rom. 3:10-12; 1 Cor. 1:18; John 6:53; John 14:16; John 3:19).
There is a third aspect to Death, eternal death. Eternal death is in a real sense the extension and finalizing of spiritual death. If one comes to physical death and is still spiritually dead (not born again), separation from God becomes permanent. As the eternal life promised by God for those who believe the Gospel is unending, so eternal death is also unending. Although in our minds we believe that death brings finality, the end, but in the instance of eternal death, we “live” on in death without hope of truly living with God ever again. Eternal death is unending separation from God and is everlasting in character (Matt. 25:31-46; Rev. 20:11-15).
Each aspect of Death, physical, spiritual, and eternal is linked to one single historical event, the sin of Adam. The Bible knows of no death of any kind occurring before the fall of Adam.