Genesis 2:15-25

15 The Lord God took the man and put him in the garden of Eden to work it and keep it. 16 And the Lord God commanded the man, saying, “You may surely eat of every tree of the garden, 17 but of the tree of the knowledge of good and evil you shall not eat, for in the day that you eat of it you shall surely die.”

18 Then the Lord God said, “It is not good that the man should be alone; I will make him a helper fit for him.”
19 Now out of the ground the Lord God had formed every beast of the field and every bird of the heavens and brought them to the man to see what he would call them. And whatever the man called every living creature, that was its name. 20 The man gave names to all livestock and to the birds of the heavens and to every beast of the field.

But for Adam there was not found a helper fit for him. 21 So the Lord God caused a deep sleep to fall upon the man, and while he slept took one of his ribs and closed up its place with flesh. 22 And the rib that the Lord God had taken from the man he made into a woman and brought her to the man. 23 Then the man said,

“This at last is bone of my bones and flesh of my flesh;

she shall be called Woman,
because she was taken out of Man.”

24 Therefore a man shall leave his father and his mother and hold fast to his wife, and they shall become one flesh.

25 And the man and his wife were both naked and were not ashamed.

What is the Tree of the Knowledge of Good and Evil?
The Tree of the Knowledge of Good and Evil is deciding for oneself, independently, what is right or wrong in one’s own eyes.

In the middle of Eden, therefore, the man and the woman face a choice: obey the Lord God and trust and accept that what the Lord God says is good or bad is good or bad—and thereby receive fruit from the Tree of Life!—or else decide for themselves what is good or bad—and thereby find themselves cut off from the Tree of Life. Later in the Bible in the Book of Judges, this deciding for themsleves will be described as “doing what is right in their own eyes.”

You can see how this choice had to be present in Eden: since God made man free, man was free to trust God, or not. Man was free to obey, and free to disobey.

He made his choice. (And so have we all.)

The rest of the Bible is the story of what the Lord is going to do to bring us back to Life.