But when the first humans took the bait of the tempter and ate from the tree of the knowledge of good and evil, they opted for an alternative way of functioning from the way God had set up for them. The tree of knowledge was attractive to them for various reasons, one of which was that it represented a way to make decisions based on their subjective and limited knowledge and wisdom. All they would have to do is to trust independently in their own thoughts and feelings and desires and not have to take the time and effort to consult a Person outside of themselves for knowledge and wisdom (which requires getting to know that Person which in turn requires dependence and time and effort). It wasn't that they didn't want God in their lives, but they saw this as a way of doing God's work more easily and efficiently.
The world system, the flesh, and the devil all agree that this is the way to govern and judge. As those who have given up personal independence to live and operate under the Lordship of God the Creator, we are faced everyday with the choice to make judgments and decisions based on one of these two trees - the tree of the knowledge of good and evil or the tree of life. The 'flesh' - that which wants to function independently of God - pulls us to make decisions according to what we subjectively believe to be 'right' or 'wrong'.
Most of us are unaware of how much emotional and intellectual energy is spent on fleshly judgments being made in a day. (Much of this happens in our hidden and often unconscious thought life and it seeps out into the open at times in judgmentalism of others.) Greg Boyd says, "Of all the sinful burdens that we place upon ourselves in our fallen state, none is weightier than the presumption that we can judge others."
Proverbs 3:5 sums up the two ways of functioning beautifully: "Trust God from the bottom of your heart (tree of life); don't try to figure out everything on your own (tree of knowledge)..." (The Message)