In Genesis 2:17 God said to Adam:
"But of the tree of the knowledge of good and evil, thou shalt not eat of it: for in the day that thou eatest thereof thou shalt surely die." (KJV)
Why did knowledge of good and evil result in death? Why is that kind of knowledge so deadly? How is this matter explained in Catholicism, Orthodoxy and main-stream Protestantism?
You ask, "Why did knowledge of good and evil result in death?" The simple answer: Because God said it would.
This is not to belittle your question. It is a good question. We need not, however, make the answer much more complicated than it needs to be. When God said "you must not . . . or you will die," he was--in modern parlance--telling it like it is. Sure enough, they did eat, and they did die, both spiritually and physically.
Perhaps related to your question, if only tangentially, is the issue of theodicy, which is an explanation for the existence of evil in the universe. Ultimately, I believe, there is no complete answer to why and how God allowed sin to enter into salvation history, going as far back as Satan's urge to be autonomous and his subsequent banishment from heaven.
An answer, but only a partial one, involves the will, or volitional ability, that all sentient creatures possess. Frankly, there is a mystery to ungodliness, and we will never have, I predict, a totally and intellectually satisfying answer to why sentient creatures have the "freedom" to disobey God.
Moreover, there are many other partial answers to that particular why. I've likened all the partial answers to theodicy to slices of pie in a pie chart. No matter how many slices the mind can generate (and each slice is an explanation unto itself), there will always be a slice with a big question mark on it. There are questions, paradoxes, and conundrums that Christians will never have complete answers to. God does, to be sure, but we do not.
The book of Job makes this very clear. If anyone had a right to ask God about why he was being put through the wringer, Job would be the man. In the concluding chapters of the book, however, God does not give Job a complete and completely satisfying answer. In the simplest terms, God tells job that he is God and Job is not. God's grasp of things and his way of thinking and doing transcend human understanding.
The Bible speaks of the "deep things" of God, things that his finite image-bearers cannot plumb fully. From Isaiah Chapter 55 come these words from the mouth of God:
“For my thoughts are not your thoughts, neither are your ways my ways,” declares the Lord. “As the heavens are higher than the earth, so are my ways higher than your ways and my thoughts than your thoughts.
In conclusion, the Bible speaks of the "mystery of iniquity" (2 Thessalonians 2:7 KJV, or "the secret power of lawlessness" in the NIV), which has been in evidence for millennia but which will reach its denouement in the awful Day of the Lord. Perhaps then, true believers will understand more than they do now about God's ways and means of dealing with sin, sin that has been a blot on humankind since our first parents disobeyed God, and whom we all followed in their disobedience.
The answer lies in grasping the significance of the Tree of Life (which I mention six times in this answer). Yet the question appears to want us to focus on the second Tree, which is just what the deceiver got Adam and Eve to do. He was out to get them believing that this other Tree would impart something desirable and vital to them (special knowledge to learn how God lives, the law that governs him, so that they could live by such law and live forever, like God.) Yet that would entail disobeying their Life-Giver, who had warned them that disobedience (not touching or eating a literal piece of fruit) would bring death.
No understanding will come until we first grasp why the Tree of Life was in the Garden. Life is the opposite of death. To live without death is what happens to humans who believe what God says on the matter of life. (Jesus confirmed that in his gospel.) Adam found himself alive in a glorious Paradise, and he conversed with his Maker. His every need was already met and there was nothing to fear. God gave him two edifying jobs - zoology and horticulture. Then he gave him a woman to help him. What more could Adam possibly desire? There was only one thing for him to reach out for, in God's due time - the Tree of Life.
He already had life, but this Tree of Life was something else, even greater than what he already enjoyed. Yet there was a danger God alerted him to. The opposite of life - death - would happen if he partook of one particular thing. "Don't do that. Don't go there. Don't think you can live as I do by choosing a different way than the one I give" (to put it colloquially).
God does not die. He is the source of all life, the great "I Am", who is utterly holy, righteous and almighty, and who gifts life eternal in Paradise to those he chooses. He does not gift life eternal to those who wilfully disobey him, for that is the path of unholiness, unrighteousness, and mortality.
Now it is time to consider God's warning about death, as epitomized by eating one forbidden 'fruit'. There was an enemy of God out to wrest God's sovereign and legal rule over his creation through deception - an illegal take-over-bid was made in Paradise, and the unseen deceiver utilized a creature in the garden to introduce an idea that would lead to death, but (obviously) without hinting at that. Quite the opposite. The deceiver first questioned what God had actually said, then ever so slightly twisted what God had said, then implied that if the humans disobeyed God they would not die but they would steal a march on God and become like him. The idea was that God was holding something back from the couple, and his warning of death was just not true - the opposite would happen. Without eating of the Tree of Life, they could grasp that divine life by knowing what this other 'fruit' was. But they had to partake of this other 'fruit', to find out. Then their eyes would be opened and they would be raised above their already glorious status as made in the image of God.
So, the answer to your question is that it was only knowledge of evil that would result in death. Knowledge of good never does. And the knowledge of God is utterly good and leads to life eternal in his pure presence. The Tree of Life was God's provision back then, and reappears in the future Paradise in heaven where its leaves are for the healing of the nations - Revelation 22:1-5. Believing what God actually says (not allowing deceivers to twist that), and obeying God's stated requirements (not doing what others say is required) is epitomized in the Tree of Life. Falling for the lie of the deceiver who uses people to obtain what is not legally his is epitomized in the Tree of the Knowledge of Good and Evil.
That's just the way I explain it, as a Protestant who has benefited from reading a couple of books that express similar thoughts on this subject. I have not quoted from those books (likewise of mainstream Protestant heritage) because huge chunks would have to be copied to do the subject justice. So you will just have to make do with my somewhat minimalistic presentation.
I'm an Anglican layman and don't know what the official position of the Church is on this. Owing to the lack of citations to Church literature, count this as a non-answer, and hold out for better ones. What follows is just my personal understanding of the subject.
I've always seen death as an act of mercy by God. Most of us live very sheltered lives and don't have true understanding of evil, and man's propensity for it. This is reflected in the popular cultural representation of devil as a guy wearing a red suite and a pitch fork, just wanting you to have a good time. Looking at evil in its raw form would be too disturbing. Pictures of crime scenes are blurred, details are omitted.
In the Bible there's extensive use of euphemisms. We think Sodom's great sin was just gay sex. It's likely it may have involved a lot more. See Marquis de Sade's rendition of this.
I wanted to link some soul shattering Wikipedia articles on human experiementation and torture, but decided against it. Won't be appropriate for this site, and you get my point anyway.
The propensity for evil is present in all. Even for those who consider themselves good, all their goodness is merely circumstantial. It's easy to look at the people in Holodomor who ate their own children and shake your head in disgust, when most of use haven't gone for a few days without food.
And it's tempting to think humans are basically good, and only commit crime due to poverty and need. Have a look at the psychopathy scale which categorizes criminals. While there are some that will kill for money or revenge, there exist some whose primary motive is pleasure derived from inflicting pain.
God who knows the end from the beginning (Isaiah 46:10) could see all of this the moment Adam bit into the fruit. (How that is reconciled with free will would be another question)
Whenever someone is under extreme duress, what they seek the most as a way out is death. Life under rebellion from God can be a worse fate than death. Something reflected in Genesis 3:22:
The man has now become like one of us, knowing good and evil. He must not be allowed to reach out his hand and take also from the tree of life and eat, and live forever.
What death does is put a limiter on mankind's evil. You can go this far and no further. Be the victim, who will escape through it, or the prepetrator like an uncaught serial killer who has to die himself at some point.
And then you have God reducing man's life from 1000 years to 120 in Genesis 6:
So the LORD said, “My Spirit will not contend with man forever,a for he is mortal; his days shall be 120 years.”
Then the LORD saw that the wickedness of man was great upon the earth, and that every inclination of the thoughts of his heart was altogether evil all the time. And the LORD regretted that He had made man on the earth, and He was grieved in His heart.
Just like good, evil takes some time to master. Imagine how faster science would progress if all the great scientists didn't keep dying of old age. The same is true for evil. A 10 year old isn't likely torture anyone. By the time they get to perfecting that as an artform, they'll be approaching end of their life.
To sum up, knowing good and evil isn't sin. Angels do. Disobedience isn't sin. Children can be innocent doing what'll be a crime for an adult. The combination certainly is a sin. And death is what God put as a damper on sin, to keep it from growing out of bounds.
One idea, that was expressed by Martin Luther, is that the tree of knowledge of good & evil was a place of worship. Here is an extended quote from Luther's Commentary on Genesis:
If therefore Adam had not fallen, this tree would have been a common temple or church, a sure palace to which all might have flocked. Thus it was afterwards, when nature was in her fallen and corrupt state, the tabernacle in the wilderness and the temple at Jerusalem were places appointed for divine worship. As therefore this "tree" eventually proved to be the cause of so awful a fall, it was rightly called by Moses "the tree of the knowledge of good and evil," on account of the horrible and miserable event which followed.
This latter tree however is called "the tree of the knowledge of good and evil," Augustine says, because after Adam had sinned by eating of it he not only saw and experienced what good he had lost, but also into what evil and misery he had been hurled by his disobedience. The tree therefore was in itself "good," even as the divine commandment attached to it was "good;" that it should be to Adam a tree of divine worship, by which he should prove his obedience to God, even by an external act of service to him. But by reason of the sin which followed, the same tree became the tree of the curse. Moses now by digressing a little proceeds to give a more extensive description of the original "garden!"
This "tree of the knowledge of good and evil," therefore, or this place in which a number of trees like unto it were planted, would have been, as we have said, a church, where Adam and his posterity, had he and they continued in their innocency, would have assembled on the Sabbath day; and Adam, after refreshment derived from the "tree of life," would have preached God to those assembled, and would have praised him for the dominion which he had given them over all other creatures he had made.
What is fascinating is that Luther held the intent of creation in the Garden of Eden, prior to the fall, was for an egalitarian view of women:
...it follows that if the woman had not been deceived by the serpent and had not sinned, she would have been in all respects equal to Adam. For her now being subject to her husband is the punishment laid upon her of God since sin and on account of sin; as are also all her other troubles and perils, her labor and pain in bringing forth children, with an infinite number of other sorrows. Woman therefore is not now what Eve was at her creation. The condition of woman then was inconceivably better and more excellent than now; she was then in no respect whatever inferior to Adam, whether you consider the endowments of her body or those of her mind.
One more thought, to enhance what Luther wrote. The tree was the tree of knowledge of tov and ra. Translating those words as "good and evil" isn't necessarily the only way to translate those words. Rather, they can actually be experiential terms.
For example, besides “evil,” Ra can be translated, trouble, distress, disaster, tragedy, affliction, adversity, harm, etc. In other words, Ra can be thought of as a negative or painful experience.
In contrast, Tov can be thought of as positive or pleasurable experiences. It involves an aesthetic that is good in the eye (and experience) of the beholder and experiencer. "And God saw the light and it was good" - meaning, he experienced it and it was pleasant to him.
Because of this, a more accurate translation would be “the tree of the knowledge of good and bad.”
Man is created from dust. He definitely needed to eat from the tree of life in order to continue to live. Angels are created differently and yet angels sinned and did not die.
God created man differently. He created two Adams and two beginnings.
God is the Potter and we are at the clay and so he set it up this way. The command God gave Adam revealed Adam's inability to obey God. We definitely saw the difference between Jesus as the son of man able to be fully obedient to God the Father.
it is written: “The first man Adam became a living being;” the last Adam a life-giving spirit. 46The spiritual, however, was not first, but the natural, and then the spiritual. 47The first man was of the dust of the earth, the second man from heaven.
The hour has come that the Son of Man may be glorified; truly, I say to you, if the grain of the wheat, having fallen to the earth, may not die, itself remains alone; and if it may die, it bears much fruit; John 12:23
It was God's intention all along that the first Adam die in order that the second Adam could come to life. This all happened in the garden that the Lord planted with the two trees.
It is through the son of man that has been glorified that started the new creation.
God gave Adam one single prohibition: Do not eat of the tree of the knowledge of good and evil. And one consequence: The day you eat of it, dying, you will die (literal).
Every other tree in the garden was freely offered with no stated negative consequence.
God, the author of all things, was exercising his singular prerogative to delineate between good and evil in articulating the prohibition.
Had Adam continually obeyed the prohibition it would have demonstrated his acquiescence to God's sovereign prerogative.
In disobeying, Adam demonstrated rebellion toward the same. Rather than trusting what God had said, Adam chose to decide for himself, thereby usurping the prerogative of God.
The serpent's temptation "In the day you eat of it you shall become like God, knowing good and evil" was realized as Adam internalized this poison and God's Word, "do not" was put to death in the father of flesh.
Thus are all humans born of flesh with the inborn disposition towards deciding good and evil for ourselves. We are born with the Word of God, as the life giving principle, dead within us; our inheritance from Adam.
Flash forward to the cross and we see the Word of God made flesh put to death by men. A perfect picture of what is killing us.
And Jesus pointed Nicodemus to that very image from Numbers 21:
And as Moses lifted up the serpent in the wilderness, even so must the Son of man be lifted up: That whosoever believeth in him should not perish, but have eternal life. - John 3:14-15
Jesus here makes a very strong and compelling simile: The serpent that Moses lifted up was an image of what was killing the people and the Son of man must be lifted up the same way. The question then becomes, How is Christ, lifted up on the cross, an image of what is killing the people?
Serpents sent by God as judgement for a heart of rebellion. The bite kills. A bronze effigy of the very thing that brings death lifted up to access life. Bronze to symbolize judgement; both the judgement of God and self-judgement.
If you look you will live. If you acknowledge God's righteousness in judging the rebellion within...if you see that which kills you, lifted up...the Word of God dead on a pole...dead in the flesh.
There is a transaction to be made and it is utterly of mercy and grace. If you will believe that this Son of God and son of man hung upon this cross to take away your rebellious disposition, this source of your death and if you will cry out to Him for salvation, He will take your death and give you His life.
The Word of God may spring to life once again within flesh as the active principle of life and, by the promise of the Father, that life can never die.
When we’re children, we jump on the bed. It’s fun. We’re not doing anything wrong. And then Mom comes in and says, “stop jumping on the bed.” We have now been made knowledgeable of the fact that jumping on the bed is wrong. If we break the rule, we’re bad. If we obey the rule, we’re good. If we don’t know the rule, we’re innocent.
Before man ate from the tree, he didn’t know right and wrong. No matter what he did, he was innocent in his ignorance. After man ate from the tree, his eyes were opened. He knew right and wrong. It is only within the bounds of that knowledge that he could knowingly choose to do wrongly. Per Genesis 4:7, our desire will be to choose sin, though we are encouraged to master sin instead. But all chose to do wrongly, per the knowledge gained by eating from the tree, and death by sin was the result, the knowledge and the inevitable consequence passed down from one generation to the next.
Different denominations have a wide variety of complicated explanations to your question, but this is the bare-bones basics.
