The believers' Church is a theological doctrine within Christianity which teaches that one becomes a member of the Church by new birth and profession of faith.

This doctrine has its origin in the Radical Reformation within Anabaptism. The 1527 Schleitheim Confession by the Swiss Brethren, a group of Anabaptists of which Michael Sattler was part, is a publication that spread this doctrine. In this confession, the believer's baptism after a profession of faith is placed as an essential theological foundation. In 1644, the 1644 Baptist Confession of Faith published by Particular Baptists stated the same. In 1916, the Pentecostal Assemblies of God Statement of Fundamental Truths stated the same too. In 1967, the Believers' Church Conference was established at Southern Baptist Theological Seminary in Louisville, Kentucky, in the United States, and is held every two or three years at a different Evangelical Bible college.

A widely accepted definition of characteristics is that of the American historian Donald Durnbaugh, who summarizes the doctrine of the believers' Church in seven points:

The doctrine of the believers' Church should not be confused with that of the free church, which is a concept designating the separate churches of states. Some Christian denominations that can be identified in the free church movement do not adhere to the doctrine of the believers' Church.

Despite the nuances in the various evangelical movements, there is a similar set of beliefs for movements adhering to the doctrine of the believers' Church, the main ones being Anabaptism, Baptists and Pentecostalism.