What was it that changed in Mans nature at the Fall?
Adam passed out of life into death. Before his fall Adam was able, at any time to eat of the Tree of Life. Had he done so he would have possessed Gods own life and lived for ever! When he fell he fell into death, lost the opportunity to possess Gods own life and thereafter became self-dependant.
What changes do we see happening internally:
......From Genesis 2:25
"And they were both naked, the man and his wife, and were not ashamed?"
......To Genesis 3:7
"And the eyes of them both were opened, and they knew that they were naked; and they sewed fig leaves together, and made themselves aprons?"
In Genesis 2:25 Adam and Eve were innocent. By Genesis 3:7 Adam and Eve were both guilty. This act of making clothes for themselves was the first self-reliant action of man. When Adam took of the fruit from Eve this was mans first independent action. Eve was deceived and as such could not have acted independently. Being deceived she was acting under an influence. Adam was not deceived and hence he acted independently. This is why sin is reckoned through Adam.
In what way were there eyes opened?
Their eyes were opened to see nakedness. Innocence precluded any knowledge of nakedness. Only after gaining the knowledge of good and evil, could they see that nakedness produces lust. Whilst innocent they were not aware nor could they experience lust. Their having been given to one another with the implication of their having union of their bodies was holy in that holiness means being set apart. Adam and Eve were created for one another physically and so their union would have been a holy act of exclusivity. Jesus confirmed this exclusivity whilst contending with the Pharisees who sought to trick him regarding marriage. As the Law of Moses had permitted divorce on the grounds of unfaithfulness they sought to set a snare for Jesus. However the Lord showed by His speech that God had not intended it [divorce] to be so from the beginning. The very fact that Adam and Eve existed alone without others, clearly establishes this fact. It would have been impossible for them to have been unfaithful. They were created exclusively for one another.
In what way did this change their nature?
Nature may mean that which is natural or it may mean the whole substance of their being. God formed man from the ground and breathed into him the breath of life, and man became a living soul. Human nature therefore must take account of spirit, soul and body in its meaning.
God said, in the day you eat thereof, you shall die. Death became their condition. Brought about through sin in disobedience resulting in separation from God as well as self reliance. Not only did death reign in Adam after the fall so also the law of sin and death reigned in his body. His soul after having acted independently of Gods commandment and warning, continued independently thereafter.
In contrast the 2nd Adam had a sinless body, acted dependently on the Father and lives forever.
What you are defining as an independent action? I guess you might be implying independent of Gods set boundaries, independent of Gods Provisions.
I think that what I have in mind in speaking of an independent action is probably the same as saying that Adam's eating of the fruit offered him by Eve, reflected Adam's power to act in disobedience to God commandment not to eat of that fruit. I have read a few times here on SI questions about why God allowed Adam to sin. My reply has always been that God didn't allow Adam to sin. God in fact forbade Adam to eat of the fruit of the Tree of Knowledge, of Good and Evil. This is not allowing. This is disallowing. In choosing to eat of this fruit Adam clearly disobeyed God. As Adam was not deceived he must have been at that moment self inclined to disobey God from his own understanding and desire. This is the meaning of independence. The real question therefore must be why did God give Adam a free will? And why was Adam inclined at that moment to disobey God? Adam was not given a choice about whether he obeyed or disobeyed God. No one has that choice. It would be absurd to believe that we can choose to disobey God. But the power of free will does make it possible to follow ones own inclinations rather than God's will. Even today for those of us who have believed in God and Christ, we still find that we are faced with the terrible reality of denying our selves in order to follow Christ, or else choosing our selves and thereby denying Christ in our actions and words.
Once that choice was made by Adam to follow His own inclination and desire he ever more makes every other action or word spoken or thought entered into, a terrible struggle between following ones own inclinations or else obeying God. This is the real meaning and consequence of independence. As it is the physical body itself which falls into and under the power of sin and death in the first instance, it is the body itself which provides the most difficult challenge. "This body of sin and death" in Romans is the physical body. When the heart and the mind are governed by this body of sin and death, the soul itself also become flesh. The reason for the flood is eluded to by a description of the decent into this carnal mind and heart of flesh by all men with the exception of Noah.
This condition is so strong that it took the giving of the Law of Moses to bring it into visibility. It took the Law of Moses to make sense of it. "Until the Law said "you shall not covet" I knew not what it was to covet"" Moreover God himself must give us the power to believe in Christ. We cannot even believe in Christ without God's saving grace and a gift of faith to believe. Independence in the end means death, because "in the day you eat thereof, you shall die". Whereas dependance means life, because through Christ's own obedience, we shall live.
Would you agree or disagree that this is the same place that infants are born into, no knowledge of good and evil and no sense of there own nakedness, and born with complete innocence?
I believe that babies are born innocent in knowledge so far as their personal experience goes. Clearly this must be the case as a baby has no initial experience. Yet we are told that no man has sinned after the likeness of Adams sin. It doesnt take long for an experientially innocent baby to become an experientially disobedient infant. On the other hand Adam was a fully developed man, yet he was also innocent. So I believe from this, that even though no one can reach adulthood and accountability without sinning, no matter how naïve or lovely they may be, they cannot be as Adam was. So no one can be an accounted adult and be innocent. One would have to ask where this knowledge of Good and Evil resides. In Genesis we read that Adam begot a son after his own image and likeness. This I believe speaks of spirit, soul and body. Just as Adam was himself created in the image and likeness of God, so his sons are in his image and likeness. Likeness must mean moral likeness and not simply physical likeness [image]. So also it must mean separation from God. Cain and Abel knew God existed, but their labours were in part set apart to God for God Himself to judge their hearts and activities. They clearly both wanted approval, yet only Abel gained approval.
Do you believe the whole substance of mans being is sin ?
What was included in this death? Spiritual, physical, relational, death from innocence or all of the above?
Please explain more of what you see this death including or being defined as?
I believe that the essential change in Adam which took place after the fall was immediate spiritual death. Which is separation from God. Whilst Adam and Eve knew immediately that they were naked, after the fall, they were still unaware that they had died spiritually. Or else that they had become separate from God. It was only after God Himself came into the garden that this condition of separation became real to them. They immediately became afraid of God Himself. Whereas they became aware of the power of sin and death in their bodies the moment they sinned. Nakedness, which previously was nothing, now became an opportunity for sin. This is the story of the physical body and the law of sin and death working in it.
The soul, even today does not always sin. Yet to the extent that a person is governed by the lusts of the body, to that extent they will sin and take pleasure in it. There are many lusts and they all produce death, or else become sin. Cain and Abel were after Adams likeness and were subject to the curse which resulted from Adams sin. We can see from their choosing their labour, in fulfilment of the curse to eat by the sweat of their brow they chose differently. This choosing shows that the soul which is the instrument of choosing (the will) does not always get it wrong. Yet for Cain his choosing was wrong and Abels was not. If the soul chooses wrongly it is not long before sin, which is crouching at the door, literally in the body, springs into action and the soul going along with the physical desire to murder, does indeed murder. Once the whole man is provoked by anger the body springs into action and the soul agrees, thereafter a man has to overcome it or else become a murderer. In Cains life he did not master it and so he murdered his brother. Today we are taught to overcome through the cross which bore Christ up unto death. All have died because one, even Christ has died for all. Through baptism we put of the old man and thereafter walk in newness of life. If we insist on walking in our own strength we will always be severely tempted by the power of sin and death working in our own bodies and the soul being overcome by the lusts of the flesh yields in agreement.