Perfectionism is the error that the believer may attain, in this present life, a state of sinless perfection or entire sanctification—a complete freedom from sin, whether by a second work of grace, an act of total consecration, or moral progress. It appears in several forms: the Pelagian, which holds sinless living possible by natural ability; the Wesleyan doctrine of ‘entire sanctification’ or ‘Christian perfection,’ in which perfect love casts out all sin; the Keswick or ‘higher life’ teaching of victory over all known sin through surrender; and various holiness and revivalist claims of a sinless second blessing. However framed, perfectionism founders on the plain testimony of Scripture and the universal experience of the saints. John writes flatly: ‘If we say that we have no sin, we deceive ourselves, and the truth is not in us’—and he writes to believers. Paul, a mature apostle, confessed he had not already attained nor was already perfect, but pressed on; and in Romans 7 he describes the ongoing war with indwelling sin. James says, ‘in many things we offend all.’ The Lord taught all His disciples to pray daily, ‘forgive us our debts.’ Perfectionism, to maintain its claim, must always either lower the standard of the law (redefining sin as only conscious, deliberate transgression, so that ignorant and involuntary sins do not count) or inflate the believer’s self-assessment, and it tends to breed either pride in those who imagine they have arrived or crushing despair in the honest soul who knows he has not. The true doctrine holds that sanctification is real and progressive but never complete in this life; the believer makes genuine progress, sin’s dominion is broken, yet its presence remains, and the war continues until death. Perfection—the full and final freedom from sin—is the believer’s certain hope, but it belongs to glorification, when he shall see Christ and be made like Him, not to this life of pilgrimage and warfare.