In the Greek world, the term ekklēsia meant a group of citizens “called out” to assemble for political purposes. In the New Testament, ekklēsia signifies a group of believers in Jesus who are called together, and is translated as “church.” The original Greek sense survives, however, when the author of Acts describes an assembly at Ephesus in which citizens have a heated discussion about Paul and his preaching (Acts 19.32, 39, 41). The city clerk finally tells people to suspend their debate until the next regular ekklēsia.

In the Septuagint ekklēsia is used interchangeably with synagogē to render Hebrew terms that mean assembly. One such occurrence from Psalm 22.22 is cited by the author of Hebrews: “in the midst of the congregation (ekklēsia) I will praise you” (Heb. 2.12).

Paul regularly uses the term church (ekklēsia) in his letters to address individual communities of believers (Rom. 16.1; 1 Cor. 1.2; 2 Cor. 1.1; 1 Thess. 1.1; 2 Thess. 1.1), and he uses the plural form to speak in general about groups such as “the churches of God in Christ Jesus that are in Judea” (1 Thess 2.14) and “all the churches of the saints” (1 Cor. 14.33). Paul does not have a developed sense of the church as a universal institution but rather sees local assemblies of believers functioning independently in separate locations. In a few cases, however, especially in reference to his persecution of the church of God (Gal. 1.3, 1 Cor. 15.9, Phil. 3.6), Paul's use of the term seems more generalized.

The term church appears only two times in the Gospels, both in Matthew. One occurrence refers to a local community's role in disputes between believers (Matt. 18.17), while in the other, Jesus uses the term church in a much more expansive sense. Matthew's Jesus responds to Peter's confession by saying “on this rock I will build my church” (Matt. 16.18). Whether the “rock” refers to Peter or to his confession is strongly debated, but either way, the verse conveys a sense of the church as a universal institution.

This universal sense is developed further in the Deutero‐Pauline letters. Ephesians and Colossians elaborate on a Pauline image by referring to the church as the body of Christ (Eph. 1.22; Col. 1.24) and to Christ as the head of that body (Eph. 5.23, Col. 1.18). In Ephesians 5.23, Christ's headship of the church is used as justification for a husband's authority over his wife.

Ignatius of Antioch (ca. 100 CE) is the earliest known author to use the phrase “catholic church” when referring to the universality of the body of Christ (Smyrneans, 8). Unanimity becomes a key concept in later discussions of the church, as orthodox leaders stress catholicity in the face of challenges from various heterodox groups. Some versions of the Nicene Creed conclude with the formula “one holy catholic and apostolic church.”

Daniel N. Schowalter