6 When the woman saw that the fruit of the tree was good for food and pleasing to the eye, and also desirable for gaining wisdom, she took some and ate it. She also gave some to her husband, who was with her, and he ate it. 7 Then the eyes of both of them were opened, and they realized they were naked; so they sewed fig leaves together and made coverings for themselves.
8 Then the man and his wife heard the sound of the LORD God as he was walking in the garden in the cool of the day, and they hid from the LORD God among the trees of the garden. 9 But the LORD God called to the man, "Where are you?"
10 He answered, "I heard you in the garden, and I was afraid because I was naked; so I hid."
11 And he said, "Who told you that you were naked? Have you eaten from the tree that I commanded you not to eat from?"
12 The man said, "The woman you put here with me—she gave me some fruit from the tree, and I ate it."
13 Then the LORD God said to the woman, "What is this you have done?"
The woman said, "The serpent deceived me, and I ate."
14 So the LORD God said to the serpent, "Because you have done this,
"Cursed are you above all the livestock
and all the wild animals!
You will crawl on your belly
and you will eat dust
all the days of your life.
15 And I will put enmity
between you and the woman,
and between your offspring and hers;
he will crush your head,
and you will strike his heel."
I've got to tell you, I find this whole story very confusing. First of all, "the knowledge of good and evil" turns out to consist of shame about the human body -- God's creation. It's possible, of course, that just happens to be the first "evil" thing they notice, but isn't it odd that God would not want the people to know good from evil in the first place?
I mean, think this through: if nakedness is evil, then the people were already sinning. Now that they've eaten the fruit, at least they stop committing that particular sin. (And I'm quite sure that the majority of Christians and Jews, and close to 100% of fundamentalists, will agree that going around naked is a sin.) So how could eating the fruit have been the original sin? On the contrary, it's the act that made it possible for people to stop sinning, if they wanted to.
Another largely unrelated observation is that God is not omniscient, not even close. He doesn't have a clue what's going on -- the people can hide from him, he doesn't know what's happened until he gets the story out of them, he is limited in time and space.
Third, he's mad at the serpent so he makes him crawl on his belly and eat dust, etc. But hey - God made the serpent. If the serpent isn't up to quality control standards, whose fault is that? And let me just add in further defense of the serpent that he did not, in fact, deceive the woman, he told her the truth. It's God who was lying.
Of course, as far as I know snakes don't actually have a problem slithering around on their bellies, that works out just fine for them. So it's not a very effective curse. Maybe God realizes that he doesn't have much of a case after all so the sentence is a light one. It is true that people tend to dislike snakes, although that's not universal, but I don't think that they care about us one way or the other.