The Holiness movement is a Christian movement that emerged chiefly within 19th-century Methodism, and to a lesser extent influenced other traditions, such as Quakerism, Anabaptism, and Restorationism. Churches aligned with the holiness movement teach that the life of a born again Christian should be free of sin. The movement is historically distinguished by its emphasis on the doctrine of a second work of grace, which is called entire sanctification or Christian perfection. The word Holiness refers specifically to this belief in entire sanctification as an instantaneous, definite second work of grace, in which original sin is cleansed, the heart is made perfect in love, and the believer is empowered to serve God. For the Holiness movement, "the term 'perfection' signifies completeness of Christian character; its freedom from all sin, and possession of all the graces of the Spirit, complete in kind." A number of Christian denominations, parachurch organizations, and movements emphasize those Holiness beliefs as central doctrine.

In addition to the regular holding of church services in the morning and evening of the Lord's Day, and usually having a midweek Wednesday church service, within parts of denominations or entire denominations aligned with the holiness movement, camp meetings and tent revivals are organized throughout the year—especially in the summertime. These are aimed at preaching the New Birth (first work of grace) and entire sanctification (second work of grace), along with calling backsliders to repentance. Churches in the holiness tradition emphasize a sober lifestyle, especially with regard to clean speech, modesty, and teetotalism.

The Holiness movement believes that the "second work of grace" (or "second blessing") refers to a personal experience subsequent to regeneration, in which the believer is cleansed from original sin. It was actually upon this doctrine, the attainment of complete freedom from sin, that the movement was built.

"In this line of thinking, a person is first saved, at which point he is justified and born again. Following this, he experiences a period of growth...This ultimately culminates in a second work of grace whereby the Holy Spirit cleanses his heart of original sin, eradicating all inbred sin. The Holy Spirit then imparts His indwelling presence, empowering the believer...This is the baptism of the Holy Spirit. It happens instantaneously as the believer presents himself or herself as a living sacrifice to God with an attitude of full consecration," and faith.

John Wesley, who articulated the doctrine, taught that those who had been entirely sanctified would be perfect in love, engaging in works of piety and works of mercy—both of which are characteristic of a believer's growing in grace.

The First General Holiness Assembly's 1885 Declaration of Principles, which explained:

"Entire Sanctification... is that great work wrought subsequent to regeneration, by the Holy Ghost, upon the sole condition of faith...such faith being preceded by an act of solemn and complete consecration. This work has these distinct elements:

The Church of the Nazarene, a large Wesleyan-Holiness denomination in the Methodist tradition, explains that: