Man is a unit of two ingredients which are material and immaterial. The material is the body and the immaterial the spirit. Both are required to be a complete person. Spiritual death is being spiritually blind and rebellious to the truth of God. Perhaps more specific would be to say it is a spiritual separation from fellowship with God because the person is at enmity with God. Genesis 3:8 may well be the best example of this separation because man “hid themselves” from God. God had told man that they would die if they ate from the forbidden tree. However, they did not physically die immediately afterwards. This must then mean that it was an immediate spiritual death but a future material body death.
Prior to the fall into sin man was in a state of innocence before God because they had never broken God’s law. Herman Bavinck said that “the Old Testament says little of the original state of integrity (Bavinck, Herman. Reformed Dogmatics. Grand Rapids: Baker Publishing Group, 2011, 317.). Adam and Eve understood the law of God because not only did God command them not to eat of the tree but they knew the consequence of breaking the law. God told them they would die if they ate of it. Had they continued to obey God they would have remained in fellowship with Him but they disobeyed and fell out of relationship. God is a Spirit and you cannot be in fellowship with Him when you are spiritually dead. Adam and Eve spiritually died when they disobeyed God. They became spiritually alienated to God because they had corrupted themselves and were now unable to bring themselves back into the relationship because of it. Ephesians 4:18 mentions man being spiritually alienated. John 3:5-7; 6:63 reveal man is not able to restore themselves outside of the work of God because they are spiritually dead.
It seems the spirit of Adam and Eve still existed but it was now in a state of deadness to a spiritual relationship. Chapter 3 of Genesis says they purposefully hid themselves from God. God exhibited grace when He came (sovereignly) looking for them. In essence the gospel can be seen here. God went after the sinner and convicted them of the sin they had committed by exposing the decision they had made. Because God loved them he mercifully saved them yet disciplined them. He sovereignly separated the will of Eve toward Satan when He said there would be enmity or hatred between them. She would no longer want to listen to Satan but to God. Even so, sin would still be present because she would still have a passion for Adam. In other word’s she would in essence covet Adams spiritual authority in the family and desire to rule her husband (Ryrie, Charles. Basic Theology. Chicago: Moody Press, 1999, 235). God’s mercy is further seen in that He made a promise to restore all things through the seed of the woman despite sin. God promised to send a savior who is of course the payment for sin. The thing they did not know was the true love of God and by doing this God was revealing something about Himself. Adam and Eve had never suffered because sin was not in the world yet. Once sin entered the world God would now mature mankind’s understanding of Himself. That is to say Adam and Eve would know more fully the concepts of God’s justice and love. God’s children now see the justice and love of God through the work of the savior, Jesus Christ.
Louis Berkhof talked about the term “original sin” and basically says that this term does not mean God created man as a sinner (Berkhof, Louis. Systematic Theology. Grand Rapids: William B Eerdmans Publishing Company, 1996, 244.). In fact, 1 Corinthians 11:7 refers to humans being “the image and glory of God” originally. Since Adam sinned all mankind is born with a corrupt flesh and spirit. Every person since that time has inherited the sin. This means everyone will physically die at some point and is born spiritually dead unless God comes looking for them, convicts them of sin, and gives them a new spirit that will love Him. This does no harm to the notion of freewill. Because of Adam’s sin, man’s will, is in rebellion to God and God must provide a new nature to a person. This new nature exercises a new will that wants to be in obedience to God. God chose to save Adam and Eve. He chooses who belongs to him and leaves others to continue in their own will/spiritual deadness. God is just to destroy sinners and did so to men, women, and children in the Bible. Continued spiritual deadness results in eternal disunity from God. The gift of eternal life is offered to everyone but narrow is the gate to heaven. It comes only through Jesus Christ the life giver. Call out to him and you will be saved.