The following was written in partial fulfillment of the requirements of Dr. Steve McKinion's Christian Theology II class at Southeastern Baptist Theological Seminary.
The theory of perfectionism suggests that believers ultimately come to a point in their present walk with God where they stop willfully sinning. This stands in contrast to non-perfectionistic views which believe the end of willful sin comes only at glorification after one’s death.
Modern perfectionism was advocated by John Wesley at some points during his ministry and adopted as a hallmark of the Wesleyan tradition (though Wesley himself abandoned the view late in life). In the Wesleyan view, the believer at some point during his life experiences a “second blessing” in which the Holy Spirit supernaturally empowers the believer to overcome the rest of his natural (fleshly) tendency toward sin. This moment must be apprehended by the believer in faith—it is not guaranteed to all believers but is granted to those who seek it in faith. The Wesleyans draw this view primarily from the apostle John’s note that “No one who lives in [Christ] keeps on sinning” (1 John 3:6), as well as from various other passages which suggest that Christians may stop sinning. Moreover, they note the biblical commands to holiness and argue that these strongly imply (if not demand) that believers be able actually to live truly holy lives. Thus, believers should pray regularly for this empowering act of the Spirit in their lives so that they may fulfill God’s will that they be truly holy.
The view has some significant and serious problems, not least in the rest of the book from which they primarily draw their support: John himself notes that when (not if) believers sin, they have an advocate with the Father in the person of Jesus himself (1 John 2:1). Similarly, the testimony of Paul and his ongoing struggles with sin after conversion and his explicit denial of having reached perfection (cf. Romans 7, Philippians 2) indicates that even for extraordinarily faithful believers, perfection will remain an unfilled but longed-for state until death.
Practically, the view readily leads to frustration and even despair on the one hand or profound hubris on the other. Those who, despite their pleading and (true!) faith do not have any experience of “second blessing” and instead remain aware of their ongoing struggle with sin may find themselves thinking they are simply weak in the faith and that they will never accomplish God’s plan for their holiness. This could not be further from the truth: those most faithfully walking with God are in fact those most aware of their own sinfulness. On the other hand, those who think they have found this holiness end up self-deceived. They proclaim their own sinlessness, and prove hypocrites. They may end up holding themselves up as superior to others (even if only in their own minds). They certainly will not go on as they ought in the process of mortifying their own sins, because they are convinced they have none.