In the beginning God created two people who were perfect in all ways. They were Adam and Eve, made in the image of God. Then they rebelled against the living God by disobeying the one commandment he had given them—eating fruit from the tree of knowledge of good and evil. I don’t think the fruit was poisonous, since there was nothing in the creation that was, but this was a test of their obedience to the Creator. For without a choice Adam and Eve would have been just ‘robots’.
As a result of their action they were cursed, as was the whole creation (Romans 8). One result of the Curse (the Fall) was degeneration in humans. This would have included errors in the genetic code, not corrected for when copies were made every time cells are replaced in our bodies. (Before the Curse God sustaining power would have corrected any thermodynamically induced copying errors.) As a result the offspring of Adam and Eve, of which there were many, would have in many ways been less than perfect, physically and mentally. They then passed these inferior traits down to all their offspring, which includes all the human race, to us.
So how can man in all his endeavours discover truth apart from revelation from God? How can we even trust our own thinking processes, since the current state of our brains is a consequence of the Curse. As a result correct human understanding of metaphysical concepts, such as eternity, the beginning and the ending of the world, as well as the past and the future destiny of all species, is extremely difficult if not impossible.
This situation has arisen due to our degenerated brains and minds being nothing like Adam’s before his fall from the Edenic state. Hence we are now without the full illumination and viewpoint of God’s spirit, which presumably provided, in Eden, an eternal and complete perspective of reality. The knowledge of good and evil passed down through the line of Adam’s descendants (including Cain) saw the development of gnostic thinking, that man with his own knowledge can discover the whole truth about the world without the Creator. But it is flawed thinking. Scripture tells us that,
He has made every thing beautiful in his time: also He has set the world [eternity] in their heart, so that no man can find out the work that God makes from the beginning [of time] to the end [of time]. (Ecclesiastes 3:11 , KJVER)
It is interesting to note the two lines of descent from Adam and Eve described in the book of Genesis; the line of Seth (who replaced Abel) and the line of Cain. The first was described as spiritual, the second carnal. Abel had simple faith and obeyed God, but Cain in his carnal mind thought he knew a better way. Sin was in his heart (Genesis 4:7). After the Fall sinful man needed God’s forgiveness. And Abel provided a suitable sacrifice, an animal sacrifice (Genesis 4:4), wherein he shed blood, because without the shedding of blood there is no remission of sin (Hebrews 9:22).
On the other hand, Cain, who also must have known this was what God required, made an offering of his own accord and choosing. He thought he knew better but God did not look favourably on his offering (Genesis 4:5). He acted in the carnal realm, using his own knowledge, which proved wrong. It seems he possibly took this to the extreme, to make amends, he thought, and sacrificed a man, his brother Abel and shed his blood. He was angry (Genesis 4:5), I assume, at God, because his sacrifice was not accepted, but he proceeded with a plan to kill his brother. So when God questioned him, “Where is your brother Abel?” he said “Am I my brother’s keeper?” It seems he felt no remorse (Genesis 4:9). But it was not what God asked.
It is worthy to note that the carnal line of Cain was the one recorded to have produced all the scientific achievements to that time (Genesis 4:20-22), presumably developed to supplement their human powers. And it seems God marked Cain making him special and in some way protected from other men (Genesis 4:15). The line of Seth on the other hand, typified later by Abraham, was the one, in the main, without a scientific program, relying rather on faith and obedience (walking with God) and so winning favour with God.
God who is living now, who fills all time and space, but who is also unchanging, thus He creates the eternal now. It is only He who can see all creation from the beginning to the end (Isaiah 46:10). He has revealed His truth through His Word. Why are there so few who are willing to give up their own strength and rely on the record that God has already given in Genesis and other books of the Bible? Jesus Christ has the answer. He said, For many are called, but few are chosen (Matthew 22:14).