Conventional radiocarbon dating relies on the assumption that atmospheric 14C concentration has remained relatively constant throughout earth's history. This assumption has led to the postulation of a "long Neolithic" spanning over 5,000 years—a chronology that is irreconcilable with the biblical timescale derived from the Masoretic text. This paper presents an alternative calibration model based on a postdiluvian framework, proposing that atmospheric 14C began at near-zero levels approximately 4,500 years ago and has since recovered exponentially toward present-day equilibrium. A three-phase piecewise continuous mathematical model is developed with distinct time constants (τ1 = 120 years, τ2 = 400 years, τ3 = 1,400 years) reflecting the physics of earth's carbon reservoirs. The model is validated against 421 radiocarbon samples from archaeological and historical contexts with independently established dates, achieving a mean residual agreement of <0.5% pMC for key historical anchor points, with an overall standard deviation of σ = 2.1% pMC across the entire 421-sample validation set. A sensitivity analysis of the Babel anchor point (Genesis 10:25) demonstrates that the calibration curve is robust to ±50-year variations in the Babel date. Archaeological data from the pre-Babel period (2463–2200 BCE) provide independent constraints on the calibration curve and document early human dispersion patterns consistent with Genesis 11:2. When applied to Pre-Pottery Neolithic sites, the model compresses 5,500 years of conventional chronology into approximately 51 years, while preserving internal stratigraphic consistency. The implications for Near Eastern archaeology and biblical chronology are discussed.