Gen 1:12 And the earth brought forth grass, and herb yielding seed after his kind, and the tree yielding fruit, whose seed was in itself, after his kind: and God saw that it was good.
The tree was not evil...I know because God told me so in His word.
I don't think the focus here is on the tree, but on the choice. God knew that Satan would tempt Adam and Eve, and if it wasn't about the tree, it would have been about something else. Satan has been using the same tactics since he rebelled against God to drive a wedge in between God and man. Satan tempts me with bitterness, lust, greed, and a multitude of other things everyday...never has he used a tree though. Probably because...
I Cor 10:23 "Everything is permissible"—but not everything is beneficial. "Everything is permissible"—but not everything is constructive. ... 25Eat anything sold in the meat market without raising questions of conscience, 26for, "The earth is the Lord's, and everything in it."...28But if anyone says to you, "This has been offered in sacrifice," then do not eat it...
Satan can't tempt me with pork, or crab anymore...I've been given permission to eat it. Therefor I won't be rebelling against God if I eat...Adam and Eve were rebelling against God when they ate the fruit. The rebellion was the sin, not the fruit.
I believe the tree was much like any other in the garden and when God put a limit on Adam and Eve He knew there was a chance they would rebel. The punishment for their rebellion was, among other things, knowledge of good and evil. The act of rebellion, or their sin, presented them with the knowledge of evil, it wasn't contained in the fruit. If they were told instead, not to touch the end of their nose with their finger and they did anyway, they would have been given knowledge of good and evil. Because they rebelled, not because evil was in their noses.
Satan corrupted them. Titus 1:15 To the pure, all things are pure, but to those who are corrupted and do not believe, nothing is pure. In fact, both their minds and consciences are corrupted. The moment they rebelled, they were corrupted and no longer pure, therefor all things were not pure (ie the fruit).
God bless,
Nigh