When the serpent first speaks in Genesis, the woman is eager to correct him. His opening speech is probably best construed, according to many modern scholars, as an incomplete subordinate clause: in Robert Alter’s translation “Though God said, you shall not eat from any tree of the garden—” (Gen. 3:1). And then the woman jumps in to tell him there is only one tree that is forbidden. So far, so good!
But she is a bit vague on which tree is actually forbidden, so the serpent responds by tacitly correcting her, directing her attention away from “the tree in the midst of the garden” (Gen. 3:3), which is the tree of life (Gen. 2:9) to the tree of knowledge of good and evil (Gen. 3:5). She is so far from disobedience at this point that he has to instruct her how to disobey by picking the right tree.
The serpent is thus not simply a purveyor of ignorance and falsehood. Like every clever liar, his words contain many elements of truth. Indeed, falsehood is unintelligible—and therefore impossible—without a whole landscape of truth in the background. How could any evil exist without a world of good things to hide in, deform and corrupt? Without the good of truth, you wouldn’t even know which fruit to eat in order to sin.
So the serpent points out that the forbidden tree is the one that will give knowledge of good and evil. It will in that sense make her like God, he says (Gen. 3:5). True enough.
But he starts by saying: “you shall not surely die!” (Gen. 3:4). That is the great lie. Yet even this lie is a half truth: she does not die the very day she eats the forbidden fruit. Some scholars, amplifying the serpent’s point, have noted that God said, “ on the day you eat of it , you shall surely die” (Gen. 2:17). What both the serpent and the scholars leave out is that this will be the day she is condemned to death. The phrase, “shall surely die” (or more literally, “will die, die,” a reduplication of the verb for emphasis) is legal terminology for the death penalty—often translated as “shall be put to death” (e.g., in Exodus 21:15-17 and Leviticus 20:10-16).
So the serpent gets the facts right about God’s word (the commandment is about the tree of knowledge, not the tree of life) but twists its meaning (as if it did not announce a death penalty). The upshot is that his lie is fundamentally about human death (“you shall not surely die!”). He leads her away from the tree of life and brings her to precisely the death he denies. For to believe his lie is to disbelieve the word of God, and that is death indeed.