Adam and Eve understood evil. Jesus Christ understood evil.
There are two ways for understanding evil.
The first way, the simplistic way, is to embrace evil. We lie, steal, cheat, commit adultery, and the like. We've tasted it and relished it. We "know" something others don't. We have a knowledge of evil because we have eaten its fruit.
The second way, the harder, more complex way, is to avoid evil and embrace the good. We refuse to take a bite of the forbidden fruit. We allow the temptation to take a bite to reach fever pitch, but in the end we have a sense that we can have a greater knowledge of evil by refusing to leave the narrow road of good. This path is more complex because we actually take a bite of goodness and that bite of goodness tastes so sweet and so wonderful that we see the danger of taking another road. The narrow path seems to be the higher path where we can look down and see the carnage of the wide road that leads to destruction. We "know" more fully the power of good and the depth of despair evil produces.
I believe this is why God told Adam and Eve to not take the bite of the knowledge of good and evil because when they did they would (and did) surely die. There was a simplistic and deadly knowledge achieved in that bite...a bite that took them and all their children (us) on a deadly path. If only they took the higher road??
Our only hope now is in the One who was tempted but without sin, whose knowledge of good and evil was so thorough that He would never take a bite of evil. And yet, though He never took a bite of evil and never wandered on the wide road to destruction, He took our deserved death and judgment. He experienced the sting of death and sin so that we could return to the path of goodness. Turn to Him. Leave the simplistic, common, and deadly path of destruction. See Christ as the Good our hearts truly desire. Jesus willingly accepts anyone who wants to leave the wide road and puts them on the narrow road to life.