Radical Pietism are those Christian churches who decided to break with denominational Lutheranism in order to emphasize certain teachings regarding holy living. Radical Pietists contrast with Church Pietists, who chose to remain within their Lutheran denominational settings. Radical Pietists distinguish between true and false Christianity and hold that the latter is represented by established churches. They separated from established churches to form their own Christian denominations.

Radical Pietism emphasizes the need for a "religion of the heart" instead of the head, and is characterized by ethical purity, inward devotion, charity, and asceticism. Leadership emphasized the sanctification of adherents instead of sacramentalism. The Pietistic movement developed in Germany, led by those who believed a deeper emotional experience was incompatible with what they saw as a preset adherence to form, no matter how genuine. They stressed a personal experience of salvation and a continuous openness to new spiritual illumination.

Many of the Radical Pietists are influenced by the writings of Jakob Böhme, Gottfried Arnold, and Philipp Jakob Spener, among others. They teach that personal holiness (piety), spiritual maturity, Bible study, prayer, and fasting are essential toward "feeling the effects" of grace.

Churches in the Radical Pietist movement include the Mennonite Brethren Church, Community of True Inspiration (Inspirationalists), the Baptist General Conference, members of the International Federation of Free Evangelical Churches (such as the Evangelical Covenant Church and the Evangelical Free Church), the Templers, the River Brethren (inclusive of the Brethren in Christ Church, the Calvary Holiness Church, the Old Order River Brethren and the United Zion Church), as well as the Schwarzenau Brethren.

Unlike Pietistic Lutherans, Radical Pietists believe in separation from the established Lutheran Churches. They believe that Christians can live through direct empowerment of the Holy Ghost rather than relying on a complex hierarchy. Churches in the tradition of Radical Pietism teach the necessity of the New Birth, in which one has a personal conversion experience to Christ. Radical Pietists emphasize the importance of holy living and thus frequently practice fasting and prayer. They also believe in non-resistance and thus "forbid Christians to shed blood."

With regard to baptism, many Radical Pietists, such as the Schwarzenau Brethren, hold to the teaching of trine (triple) baptism: "that the original and apostolic form of baptism was to immerse the candidate forward into the water three times (once in the name of the Father, once in the name of the Son, and once in the name of the Spirit)." Radical Pietists, such as the Schwarzenau Brethren and the River Brethren, also practice the lovefeast, which includes footwashing and the holy kiss, as well as closed communion. The Radical Pietistic communities do not believe in the swearing of oaths. They resolve problems in the community at the congregational level under church councils presided by elders, rather than in civil courts. Members who sin openly are visited by the elders and encouraged to repent of their transgressions.

Churches in the Radical Pietist movement include the Baptist General Conference, the Community of True Inspiration (Inspirationalists), members of the International Federation of Free Evangelical Churches (such as the Evangelical Covenant Church and the Evangelical Free Church), the Mennonite Brethren Church, the Templers, the River Brethren, and the Schwarzenau Brethren.

Converge, formerly known as the Baptist General Conference, emerged as a result of Radical Pietism spreading in Sweden. The denomination emerged among Radical Pietists who separated from state churches and emphasizes the doctrines of "believer's baptism, a believer's church, free access to read and study Scripture, the importance of prayer and other spiritual disciplines, and a lifestyle that exhibited separation from sin."