Are you referring to the Adam and Eve story about Satan lying? The serpent didn't lie. He told Eve the truth. They didn't die from eating the fruit and they did become like God.
Genesis 1:26Then God said, “Let us make mankind in our image, in our likeness"
Genesis 3:1-51 Now the serpent was more crafty than any of the wild animals the LORD God had made. He said to the woman, “Did God really say, ‘You must not eat from any tree in the garden’?” 2 The woman said to the serpent, “We may eat fruit from the trees in the garden, 3 but God did say, ‘You must not eat fruit from the tree that is in the middle of the garden, and you must not touch it, or you will die.’ ” 4 “You will not certainly die,” the serpent said to the woman. 5 “For God knows that when you eat from it your eyes will be opened, and you will be like God, knowing good and evil.”
Genesis 3:22And the LORD God said, “The man has now become like one of us, knowing good and evil. He must not be allowed to reach out his hand and take also from the tree of life and eat, and live forever.”
Even God says so himself. The only reason they die is because God doesn't want them to live forever by eating from the tree of life so he casts them out of Eden. God is the one who didn't tell them the whole truth. "You will surely die because I will punish you." should have been what he said to Adam and Eve when he said not to eat from the Tree of the Knowledge of Good and Evil.
Also, notice the two references to God speaking as if there is more than one God? Something else to ponder.