The question of church membership may be approached from various points of view: the theological, the juridical, and the sociological. The theological approach, which will be emphasized here, grows out of the biblical foundations of the Christian faith.

Old Testament

The "people of God" are identified with Israel as an ethnic group and a nation in various books of the Old Testament (Dt. 7:7–8, Is. 41:8, 51:2, etc.). By birth the individual received the call to live up to the religious heritage of the people. Especially in the Judaism of the Diaspora, non-Israelites who believed in the God of Israel were admitted to the ranks of the proselytes and could, through circumcision and immersion, become Israelites in the full sense. A person who was once an Israelite could be put under the ban, or could apostatize, but could not cease to be a member of the people of God...