The Reformation marks of a true church form the dominant theological grid of many Protestant theologians and pastors today, namely, the right preaching of the Word of God and the right administration of the sacraments (Calvin, Institutes 4.1.9; Thirty-Nine Articles, Art. 19). Sometimes church discipline is added as a third mark (Belgic Confession, Art. 29). If a church has these features, so it is thought, the church is a genuine congregation under the lordship of Jesus. Nevertheless, these marks present a problem. Churches that hold to the Reformation marks and disagree with other congregations on the mode or subjects of baptism, for example, should not consider those assemblies true churches if they are being logically consistent. That would mean that most Baptists, who baptize believers only (subjects) by immersion only (mode), should reject Presbyterian, Congregationalist, Anglican, and Methodist churches as genuine, and likewise, these latter traditions should not recognize Baptist churches as genuine. What insights can the apostle Paul provide?
This paper uses First Corinthians as a case study to argue that Paul affirms only one absolutely necessary mark of a church—the right preaching of the Word according to the gospel. The gospel must be accepted by a church’s constituents for it to be considered a genuine Christian assembly. First, I will argue that Paul considers the Corinthian church a true “church of God,” defined as those who “call on the name of our Lord Jesus Christ” (1 Cor 1:2). The essence of a true church is defined by belief in the core message of the gospel (cf. also Eph 1:1; Col 1:1). Second, Paul affirms that his ministry is not to baptize but to preach the gospel (1 Cor 1:17). Baptismal papers are in disarray in Corinth (1:14–16), yet Paul still considers it a true church (Blomberg). Third, what is taking place among the Corinthians under the guise of “the Lord’s Supper” is not really that event at all—in reality, each individual eats “his own” supper (11:20)—yet Paul still recognizes the Corinthian congregation as a true “church” (v. 18, 22). Fourth, the Corinthian congregation is not consistently practicing church discipline (5:1), yet it is still considered an assembly in which the Lord Jesus is present (v. 4). Paul’s ministry to the church in Corinth provides a helpful biblical correction to the dominant Protestant paradigm of the Reformation marks.