Nicholas Batzig has a nice meditation on the trees in the Garden of Eden and the cross of Christ in his blog post
A Biblical Theology of the Trees of the Garden. Here are a few comments about the Tree of the Knowledge of Good and Evil:
This tree was a symbolic representation of what man could attain to, either by obedience or disobedience; it was a probation. Geerhardus Vos explained:
1. By this tree it would be made known and brought to light whether man would fall into the state of evil or would be confirmed in the state of immutable goodness.
2. By this tree man, who for the present knew evil only as an idea, could be led to the practical knowledge of evil. Or also because he, remaining unfallen, would still, by means of temptation overcome, gain clearer insight into the essence of evil as transgression of God’s law and disregard of His sovereign power, and likewise would attain the highest knowledge of immutable moral goodness.2
Vos explained elsewhere how Satan sought to pervert the meaning of the Tree of the Knowledge of Good and Evil when he wrote:
From the true conception of the purpose of the tree we must distinguish the interpretation placed upon it by the tempter according to Gen. 3.5. This carries a twofold implication: first that the tree has in itself, magically, the power of conferring knowledge of good and evil. This lowers the plane of the whole transaction from the religious and moral to the pagan-magical sphere. And secondly, Satan explains the prohibition from the motive of envy. … Again, the divine statement in Gen. 3.22 alludes to this deceitful representation of the tempter. It is ironical.3
Adam did indeed attain to the knowledge of good and evil, but, as Vos noted, he attained it from the standpoint of becoming evil and remembering the good in contrast to the evil he performed. He gained the experiential knowledge of good and evil from the evil side. If we make Genesis 1-3 our starting point, and then consider all the occasions in which man is called to make judgments (i.e. to decided between good and evil in each and every situation) we soon discover that he is always prone to choose the evil over the good in his natural state. When the LORD comes to assess Israel’s actions through the prophet Jeremiah this is what He concludes: ” For My people are foolish, they have not known Me. They are silly children, and they have no understanding. They are wise to do evil, But to do good they have no knowledge (Jeremiah 4:22). A little later on the Lord says of Israel, “‘they proceed from evil to evil, And they do not know Me,’ says the LORD.” It was knowledge of the LORD that was the knowledge of good that men lack. There are many similar verses in the prophets, in which the LORD brings the charge that men, including His people Israel, had not learned how to do good.
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2. Geerhardus Vos (2012–2014). Reformed Dogmatics. (A. Godbehere, R. van Ijken, D. van der Kraan, H. Boonstra, J. Pater, & A. Janssen, Trans., R. B. Gaffin, Ed.) (Vol. 2, pp. 28–29). Bellingham, WA: Lexham Press.
3. Vos, Geerhardus Biblical Theology (1948), pp. 27-33.
