Mortification of Sin is John Owen's classic treatise on sanctification, expounding Paul's charge in Romans 8:13 with Puritan precision and pastoral urgency. Owen dissects the anatomy of indwelling sin, distinguishes counterfeit mortification from Spirit-wrought obedience, and prescribes a disciplined regimen grounded in union with Christ, the Word, prayer, and watchfulness. Written in tightly argued propositions and practical casuistry, it refuses both ascetic self-reliance and lax antinomianism, pressing the memorable axiom: "be killing sin, or sin will be killing you." An Independent divine and vice-chancellor of Oxford during the Interregnum, Owen (1616-1683) combined classical learning with relentless pastoral inquiry. Composed in the mid-1650s alongside companion essays on temptation and indwelling sin, this work arose from university sermons and counsel amid civil turmoil, sectarian excess, and moral weariness. Owen writes as a physician of souls shaped by Reformed scholastic method, personal affliction, and disputes with both legalists and libertines. Readers of theology, pastors, and serious laypeople will find in Mortification of Sin a bracing, deeply consoling manual for growth in holiness. It rewards slow, reflective study, offering diagnostics and remedies that remain startlingly contemporary for anyone intent on resisting sin by the Spirit. Quickie Classics summarizes timeless works with precision, preserving the author's voice and keeping the prose clear, fast, and readable-distilled, never diluted. Enriched Edition extras: Introduction · Synopsis · Historical Context · Brief Analysis · 4 Reflection Q&As · Editorial Footnotes.