The Church’s Mere Identity
Unlike the world and its character of sinfulness, the church is characterized by holiness.
The early church’s creeds offer the following affirmations:
Apostles’ Creed: “I believe in the holy catholic church.”
Nicene-Constantinopolitan Creed: “We believe in one, holy, catholic, and apostolic church.”
Importantly, both creeds confessed their ecclesiological belief in terms of the essence or attributes of the church rather than its ministries or roles. In part, this emphasis had to do with the church’s aim to define itself over against heretical groups that had separated themselves from the church while still claiming to be genuine churches.  Of note are four essential identity markers: oneness, holiness, catholicity, and apostolicity.
The church is characterized by unity, especially in relation to sound doctrine. As Irenaeus affirmed early on,
The church, though dispersed throughout the whole world, even to the ends of the earth, has received from the apostles and their disciples this faith . . . [and] as if occupying one house, carefully preserves it. It also believes these points [of sound doctrine] just as if it had only one soul, and one and the same heart. It proclaims them, teaches them, and hands them down, with perfect harmony, as if it possessed only one mouth.
This attribute of oneness finds substantial biblical support, from Jesus’s high priestly prayer that his followers be united (John 17:11, 21–23) to Paul’s insistence that the Holy Spirit grants unity to the church, especially with regard to being one body with one Spirit, hope, Lord, faith, baptism, and Father (Eph. 4:1–6; cf. 4:13). The church, then, is identified by its oneness, especially its unity in doctrine.
Unlike the world and its character of sinfulness, the church is characterized by holiness. This purity is positional, in the sense that the holy church is set apart for, or consecrated to, God and his purposes. Regretfully, the church is not always and everywhere empirically identifiable as holy, given its continued sinfulness as part of its living a liminal existence—already but not yet pure. This matter-of-fact unholiness did not stop early church leaders from calling their members to break from their sinfulness and pursue purity, underscoring this attribute. As Justin Martyr intoned, “Let it be understood that those who are not found living as Christ taught are not Christians, even though they profess with the lips the teachings of Christ.” Aware of the fragmentary nature of its present holiness, the church yearns for its future unveiling as “the holy city, new Jerusalem,” the radiant bride of Christ, clothed in his perfect holiness (Rev. 21:2).
Biblical support for this attribute includes references to the church as a sanctified, saintly assembly (1 Cor. 1:2; cf. 1 Pet. 2:9) and exhortations to the church to live as a holy people (1 Pet. 1:14–16). Therefore, an identity marker of the church is its holiness.
Rather than referring to the particular Roman Catholic Church, catholicity refers to the church’s universality (Gk. katholikos, “universal”). The church is catholic because of (1) the presence of Christ in it and (2) the universal commission given to it by Christ. Regarding the first reason, Ignatius offered, “Where there is Christ Jesus, there is the Catholic Church.” As for the second reason, Christ commissioned his disciples with the following order: “Go therefore and make disciples of all nations, baptizing them in the name of the Father and of the Son and of the Holy Spirit” (Matt. 28:19). This Great Commission is universal in scope. As explained by Cyril of Jerusalem, the church is catholic
because it extends over all the world . . . and Because it teaches universally and completely one and all the doctrines which ought to come to men’s knowledge . . . and because it brings into subjection to godliness the whole race of mankind . . . and Because it universally treats and heals the whole class of sins . . . and possesses in itself every form of virtue which is named, both in deeds and words, and in every kind of spiritual gifts.
In contrast to a peculiar splinter church (like that of Donatus or Novatian), the true church is catholic. Consequently, Ignatius issued a warning: “Whoever does not meet with the congregation [Gk. ekklēsia, ‘church’] thereby demonstrates his arrogance and has separated [or judged] himself.” As already noted, this characteristic of universality is well supported biblically by Jesus’s Great Commission (Matt. 28:18–20; Luke 24:44–49; Acts 1:8), with the corollary that people who seek to divide the church are to be removed from the church (e.g., Rom. 16:17–18; Titus 3:10–11). They are an impediment to its universality, which is an attribute of the church.
The church is characterized by adherence to the teachings of the apostles. Such apostolicity stands in contrast with heretical groups, which invent and promote false doctrine. As Tertullian explained,
From this we draw up our rule. Since the Lord Jesus Christ sent the apostles to preach, our rule is that no others ought to be received as preachers than those whom Christ appointed. . . . Now, what they preach—in other words, what Christ revealed to them—can . . . properly be proved in no other way than by those very churches which the apostles founded in person. They declared the gospel to them directly themselves, both viva voce [by live voice] . . . and subsequently by their writings. If, then, these things are so, it is equally clear that all doctrine which agrees with the apostolic churches—those matrixes and original sources of the faith—must be considered truth, undoubtedly containing that which the churches received from the apostles, the apostles from Christ, and Christ from God.
Churches founded by the apostles in the early Christian movement were custodians of sound doctrine; thus, they were to be heeded. In turn, these apostolic churches planted other churches—second-generation apostolic churches—and so the line continued. Heretical groups did not possess such a lineage; they were not able to trace their origins to first-generation apostolic churches and, more importantly, to the apostles themselves. Accordingly, they were false churches.
Most importantly, the church is apostolic in the sense of adhering to the teachings of the apostles, as those doctrines and practices were written down in Scripture. This idea of apostolicity has firm biblical support, from the foundational role of the apostles (Eph. 2:20) to the authoritative instructions given by the apostles (1 Cor. 14:37; 2 Thess. 2:15; 3:4, 6, 10, 12; Titus 1:3; 2 Pet. 2:3). By heeding this apostolic teaching, the church demonstrates its characteristic of apostolicity.
In summary, the early church’s creedal confession of the identity markers of the church—oneness/unity, holiness/purity, catholicity/universality, and apostolicity—represents a historical precedent of the mere identity of the church.
1. For further discussion, see Gregg R. Allison, Historical Theology: An Introduction to Christian Doctrine (Grand Rapids, MI: Zondervan, 2011), 567–69.
2. Irenaeus, Against Heresies, 1.10.1–2, in Ante-Nicene Fathers (henceforth ANF), ed. Alexander Roberts (Peabody, MA: Hendrickson, 1994), 1:330–31. The text has been rendered clearer.
3. Justin Martyr, First Apology, 16, in ANF, 1:168. The text has been rendered clearer.
4. Ignatius, Letter to the Smyrneans, 8 (shorter version), in ANF, 1:90. Later, Irenaeus would add, “Where the church is, there is the Spirit of God; where the Spirit of God is, there is the church.” Irenaeus, Against Heresies, 3.24.1, in ANF, 1:458.
5. Cyril of Jerusalem, Catechetical Lectures, 18.23, in Nicene and Post-Nicene Fathers of the Christian Church, 2nd ser., ed. Philip Schaff and Henry Wace (1890–1900; repr., Peabody, MA: Hendrickson, 1994), 7:139–40.
6. Ignatius, Letter to the Ephesians, 5, in ANF, 1:51.
7. Tertullian, Prescription against Heretics, 21, in ANF, 3:252. The text has been rendered clearer.
8. Tertullian, Prescription against Heretics, 32, in ANF, 3:258.