Did you ever notice that Adam didn’t do anything to bring on the temptation? He didn’t leave a gate open that God told him to close, and then get a snake in the Garden. He was doing everything right, and the snake showed up anyway. Trouble and temptation are not the result of the Fall; they’re the occasion for it. Man is born for trouble; that’s just part of the Story God is telling.
When I teach Creation and the Fall to my middle-school kids, they unfailingly ask about the Tree of the Knowledge of Good and Evil: “Why did God put that tree in the Garden to start with?” The answer is that it was a tool for Adam’s maturation. That Tree was God’s gift to Adam and Eve, the site where they would learn good from evil. In biblical terms, knowing good and evil is not a bad thing; it’s a way in which we become like God — as God Himself says in the account (3:22). God will later bless Solomon for asking for this exact thing (1 Kings 3:9).
In order to live in the world God had made for them (which included the serpent), Adam and Eve would need knowledge of good and evil. The Tree would have been the site where Adam and Eve attained knowledge of good and evil one way or the other, but they were meant to gain knowledge by resisting temptation, not by yielding to it. By yielding, they seized knowledge by illegitimate means, and died.
The Tree is a gift, but it’s like someone giving you a chainsaw for Christmas — it’s a good gift, but if you handle it badly, it’ll kill you all the same. The biblical account teaches us that knowledge of good and evil is inherently dangerous, and do notice that it’s not just knowledge of evil. There is a knowledge of good that can kill you too. The vital thing is to handle the gift in the way God tells us to handle it.
Adam and Eve had been given everything they needed to know to handle the temptation in front of them. If they’d simply remembered God’s instructions, if they’d waited until the cool of the day to meet with God and ask Him what He thought, if…. But they didn’t.
By way of analogy, imagine a kid whose parents own a bed & breakfast. Reaching the age where he’s curious about sex, the kid conceals a camera in someone’s room on their wedding night. What the kid observes is a Good Thing, but him observing it is not! The way he’s supposed to acquire that knowledge is by participating in his own wedding night in due time, not by watching someone else’s. Grasping illegitimately for that knowledge is sin, it damages him, and he doesn’t really learn the same things that he would have if he’d waited and gone about it the right way.
So it is for us. Knowing good and evil is becoming more like God, but we don’t need to grasp after it. He will take us there in the right way. Our job is to trust Him and be faithful to what He has already given.
Full Contact Christianity 
May I introduce the true account of what took place in The Garden:
Did Eve Have Sex With The Devil or Did She Just Eat Some Fruit?: