The original sin was committed by Adam and Eve. God directly commanded Adam that he was not to eat of the tree of the knowledge of good and evil. Gen 2:17. The serpent deceived Eve by making her doubt God’s warning. She believed that this knowledge would be profitable so she persuaded her husband to eat with her. Gen 3:4-6. They now had the knowledge of good and evil. This knowledge brought with it guilt for they knew that they had done evil by disobeying God’s only law. Consequently God cast them out of the Garden of Eden so that they would not eat of the tree of life and live forever in their fallen, disobedient state. Gen 3:22-24
We too bear the same penalty as Adam and Eve. We do not have access to the tree of life. Death is the consequence that they passed onto us, their descendants. The knowledge that Eve so desired has also been passed down from generation to generation but the nature of mankind was not corrupted by Adam and Eve’s sin.
Babies are born as innocent as Adam and Eve were when they walked with God in the Garden (Gen 2:25) before the fall. As children grow, they are taught what is good and what is evil. They then reach a level of understanding and maturity when they are able to decide for themselves which direction to take. Their innocence is corrupted when they yield to sinful desires. The Bible states that every person (Rom 3:23),, except one (Heb 4:14-15),, has succumbed to worldly temptations. Mankind did not inherit a sinful nature from Adam and Eve.
Romans 3:10-18 is cited as proof that mankind inherits a sinful nature. These verses are quotes taken from the Old Testament, notably the Psalms. Psalms 14:1-3. which states that “the fool hath said in his heart, There is no God. They are corrupt, they have done abominable works , there is none that doeth good” is taken to mean that even babies are corrupt. Paul’s purpose in this chapter was to show to the Jews that they were as corrupt as the Gentiles to whom they felt superior (Rom 3:9). Corruption is a matter of choice of thought or action against God. David himself stated so in Psalm 14:1 “they have done abominable works” and in Ps 5:10,” for they rebelled against thee.” Babies are incapable of choosing to think or act against God.
Hebrew poetry is filled with figurative language. Psalm 51:5 states “Behold, I was shapen in iniquity; and in sin did my mother conceive me.” Psalm 58:3 describes the wicked as going astray from the womb. This is not a literal statement because babies are not born with the ability to speak. In Ps 139:14-15, David states “I will praise thee for I am fearfully and wonderfully made: marvelous are thy works and that my soul knoweth right well. My substance was not hid from thee, when I was made in secret, and curiously wrought in the lowest parts of the earth.” In Ps 22:9-10, David says to God, “ but thou art he that took me out of the womb, thou didst make me hope when I was upon my mother’s breasts. I was cast upon thee from the womb, thou art my God from my mother’s belly.” David’s emotions of grief or exultation are reflected in his poetry. Psalms uphold the belief that man is born good and without sin.
Babies and children are upheld as a model of purity in other Bible verses as well. In Matthew 19:14, Mark 10: 14-16 and Luke 18:16-17, Jesus extols children as an example of those who will enter the kingdom of God. Adults are to be converted and become like children. (Matt18:3) Paul tells the brethren to be like children in their lack of malice. (1 Cor 14:20) Malice is kakia in Greek and is defined as "badness in quality or the vicious character generally" in Vine's Expository Dictionary of Old and New Testament Words. Strong's Comprehensive Concordance of the Bible further describes kakia as depravity.
A sinful nature is not inherited.
Mankind’s inherent nature has not changed since Adam and Eve’s. This couple only lacked the knowledge of good and evil. (Gen 2:17). Children too lack this knowledge. In Deuteronomy 1:34-39, God did not hold the children accountable for their parent’s decision of sinfulness. The nature that Eve demonstrated in the Garden (Gen 3:6) when she lusted for the fruit of the Tree of Knowledge of Good and Evil, exists now (1 John 2:16). Jesus had the same nature as us, but through His closeness and obedience to the Father as His Son, He did not give into the temptations that were very real in His life ( Matt 4:1-11; Heb 2:18). Even though babies are born sinless at birth, they can not return to the Garden of Eden because the tree of life is guarded by cherub with a flaming sword. (Gen 3:24). Death is the consequence of that original sin, not an inheritance of a nature in which there is no free will to choose good or evil for ourselves.
The original sin was an act of choice by Adam and Eve. It is not an inherited state of humanity. The psalms poetically describe mankind’s goodness from conception. New Testament passages of Jesus and Paul instruct us to be like children. Sin entered the world through Adam and Eve’s choice of disobedience. (Rom 5:12) and through that sin, the consequence of death but human nature has been the same from the beginning, beings with free will.
“ Butter and honey shall he eat, that he may know to refuse the evil, and choose the good.” Isaiah 7:15
The Gospel Truth by Alfred T. Overstreet
Minutes with Messiah -questions answered on line by Tim O'Hearn
Original Sin doctrine on Wikipedia