When we read in Genesis 2:17, do we not subconsciously read into it, "Yes, but He does not really mean that. He means we will eventually die"? We soften it, expecting that God will not carry through with what He literally says.
The Keil-Delitzsch Commentary says about this verse, "That in the day that you eat thereof you shall die." It means as soon as he ate, he would die. The Keil-Delitzsch is a very conservative commentary. The Interpreter's Bible Commentary, which is one of the most liberal commentaries, says, "Death would follow immediately!" From one of the most conservative commentaries, Keil-Delitzsch, to one of the most liberal, The Interpreter's Bible Commentary, they agree the verse says that when they touched that tree, thus showing the intent of their heart, they would die.
In the beginning, at creation, all sin is deemed as worthy of death. Every sin is a capital offense. In creation, God was not obligated in any way to give life to you or me. Life is a gift that puts us under obligation, and that obligation is stated, or at least implied very strongly, right when man is being created. God gave life to man and put him under the obligation of being the image-bearer of God (Genesis 1:26). That is why we were created.
In chapter 2, we are further obligated by God's command to take of the Tree of Life, and not the other tree. The implication there is that only God knows how we are to live in order to fill our obligation to be the image-bearer of God. We have to learn that the root of sin lies in the desire of men to live their lives in self-centered independence from God. This is what keeps us from being the image-bearers of God that He intended us to be. If we deviate from this, have we not broken our obligation to God? If we deviate from this—if we go from the path, if we miss the mark—we have sinned. We have broken our obligation to mirror and reflect the holiness of God.
Implied by the name “Tree of Life,” God is telling us that we do not intrinsically possess the kind of life that God has, and that if we want that kind of life, it must be added. It is added through what the Tree of Life symbolized. What if we do not meet our obligations? We forfeit the gift of life when we sin.
Is God unfair if something is so clearly stated? Do we see why He commands us to choose life? He sets before us two different ways. He commands us to go in a certain direction, because if we go in the other direction we have broken our obligation to be image-bearers, and then He is not obligated any longer after that to continue our lives. He is under no obligation to continue the life that He gave to us as a gift. God is not acting unfairly nor with injustice, for the commands are very clear.
When the penalty was stated to Adam and Eve, did God say, "If you sin, some day you will die"? No. The penalty is clearly stated to be instant death, just as suddenly as it fell on Nadab and Abihu, and on Ananias and Sapphira, and Uzza.
Let us look at this realistically and let us not try to soften what God very clearly and literally says. He meant the death penalty in the fullest sense of the word. The only reason they lived was because it was right at that point that God extended grace. God was no longer obligated to continue their life.
They had broken His Word, deviated from the path, and the just thing for God to have done would have been to kill them just as He did Uzza. That is not what He did though. Instead, He gave them mercy, and He gave them grace. There is a saying, "Justice delayed is justice denied," but not always so. In this case with Adam and Eve, the full measure of justice was delayed for grace to have time to work.
We need to be thinking of this in relation to ourselves, because He is establishing a pattern. Justice was delayed so grace would have time to work. In this case, the delay of justice was not the denial of justice, but the establishing of mercy and grace. So right at the very beginning of the Book, in its third chapter, grace is introduced.