Genesis 2:17 has God warn Adam, 'in the day that you eat of it you shall die.' Adam and Eve ate the fruit and did not die that day; they went on to live for centuries (Adam died at 930, Gen 5:5). Therefore God lied.

This is a real interpretive question, not a dodge, and it deserves to be engaged on the actual Hebrew. **The grammar.** The Hebrew is מוֹת תָּמוּת (*mot tamut*), an infinitive absolute followed by the finite verb from the same root. This is a standard Biblical Hebrew intensifying construction (Waltke & O'Connor, *An Introduction to Biblical Hebrew Syntax*, §35.3.1) used throughout the Torah and historical books — most visibly in the legal death-penalty formula *mot yumat*, 'he shall surely be put to death' (e.g. Exod 21:12, 21:15, 21:17; Lev 20:10). Its grammatical function is to intensify the certainty and inevitability of the verbal idea ('dying, you shall die' / 'you shall surely die'), not to fix a rigid clock on when the outcome must be completed. Robert Alter, in his translation and commentary on Genesis, renders it 'doomed to die' precisely to capture this — the construction announces an irrevocable sentence, not a stopwatch. The same idiom appears in contexts (e.g., 1 Kings 2:37, 42, where Shimei is told on what day he will be 'certainly put to death' if he crosses the Kidron, and is in fact executed only after a subsequent violation) where the emphasis falls on the certainty and legal force of the verdict, not on instantaneous same-hour execution. **The theological content — mortality as the sentence, not a missed deadline.** The narrative's own follow-through in Genesis 3 makes clear what 'you shall die' means: Genesis 3:19, 'for dust you are, and to dust you shall return,' introduces human mortality as a now-fixed condition where death had not previously been humanity's horizon. Genesis 3:22–24 is decisive: God expels the couple from the garden specifically 'lest he reach out his hand and take also from the tree of life, and eat, and live forever' — implying that continued access to that tree had been sustaining unending life, and that access is now permanently barred. Paul reads the episode the same way in Romans 5:12: 'sin came into the world through one man, and death through sin, and so death spread to all.' The sentence is pronounced and takes legal effect the day of the transgression — access to life is cut off that day — even though its full execution (physical death) unfolds over a lifetime. This is exactly the structure of a judge sentencing a defendant to death 'today': the sentence is real, binding, and true the moment it is pronounced, without requiring the execution to be literally instantaneous. **The relational/spiritual dimension, fulfilled immediately.** Serious Genesis commentators press further: the consequence actually narrated as happening *that day* is relational rupture with God — the couple hide from God's presence (Gen 3:8), are addressed in judgment, and are driven out of the garden, the locus of unmediated fellowship with God. Gordon Wenham (*Genesis 1–15*, WBC) and Bruce Waltke (*Genesis: A Commentary*) both treat this expulsion/separation as the primary sense in which death is realized 'that day' — covenantal and relational death (separation from the source of life) alongside the now-inaugurated mortality that follows. Both readings converge: the threatened death is not falsified, it is inaugurated the day of the sin and worked out from there.

Classical theism does not treat God's truthfulness as an external rule God happens to obey; it flows necessarily from what God *is*. On the Thomistic account, truth is a transcendental convertible with being itself (Aquinas, *Summa Theologiae* I, q.16), and divine simplicity means God's word is not a separable act distinct from God's own being (ST I, q.3) — so a 'lying God' is not merely a morally deficient God but a metaphysically incoherent one, an entity whose nature would have to be non-self-identical. Numbers 23:19 ('God is not a man, that he should lie') and Titus 1:2 ('God, who never lies') are read in this tradition not as pious reassurances but as claims about God's essential nature.