Restorationism (or Christian primitivism) is the belief that Christianity has been or should be restored along the lines of what is known about the apostolic early church, which restorationists see as the search for a purer and more ancient form of the religion.[1][2][3] Fundamentally, "this vision seeks to correct faults or deficiencies (in the church) by appealing to the primitive church as a normative model."[1]:635

Efforts to restore an earlier, purer form of Christianity are often a response to denominationalism. As Rubel Shelly put it, "the motive behind all restoration movements is to tear down the walls of separation by a return to the practice of the original, essential and universal features of the Christian religion."[4]:29 Different groups have tried to implement the restorationist vision in a variety of ways; for instance, some have focused on the structure and practice of the church, others on the ethical life of the church, and others on the direct experience of the Holy Spirit in the life of the believer.[1]:635–638 The relative importance given to the restoration ideal, and the extent to which the full restoration of the early church is believed to have been achieved, also varies among groups.

In comparable terms, earlier primitivist movements, including the Hussites,[5]:13 Anabaptists,[5]:125–135 Landmarkists,[5]:69–71 Puritans,[5]:50–55 and Waldensians have been described as examples of restorationism, as have many seventh-day Sabbatarians. For Anabaptists, restoration primarily meant to relive in a studied fashion the life of the New Testament.[6] Landmarkism (often identified with Baptist Successionism) is more properly a theory of the continuation of the pure Church through the centuries, recognizable by certain key doctrines, primarily believer's baptism. Many groups have attempted a history of their movement and an ecclesiology that falls somewhere in between the two ideas of Restorationism and Successionism.

The term "restorationism" is sometimes used more specifically as a synonym for the American Restoration Movement.[2]:225–226 The term is also used by more recent groups, describing their goal to re-establish Christianity in its original form, such as some anti-denominational Charismatic Restorationists, which arose in the 1970s in the United Kingdom and elsewhere.[7][8]