When Did the Church Begin? This question is not uncommon, especially among theological students. Sometimes people ask it because they have been exposed to dispensational teaching. In that case, the answer one gives becomes a kind of litmus test to a nest of other questions that dispensationalists pose. People from a dispensational heritage emphasize discontinuity between the covenants, and therefore commonly argue that the church begins at Pentecost; people from a covenant-theology heritage emphasize the continuity of the covenant of grace, think in terms of fulfillment of what was promised, and therefore argue that the “assembly” of the people of God is one, and that therefore it is a mistake to argue that the church begins at Pentecost. Others ask the question in our title because for them the answer is a way of distinguishing between Reformed Presbyterians and Reformed Baptists. Still others ask the question without a theological agenda, but for no other reason than that it deserves to be asked precisely because the answer seems ambiguous in the biblical texts.
It may be helpful to organize the relevant material in several steps.
(1) As for the terminology, although “church” is commonly a NT expression, both the word and the idea surface in the OT too. For example, a not atypical passage pictures God instructing Moses, “Assemble the people before me to hear my words so that they may learn to revere me as long as they live in the land and may teach them to their children” (Deut 4:10): the verb is קהל in Hebrew and ἐκκλησιάζειν (cognate with ἐκκλησία, “church” or “assembly”) in the Septuagint. Not less important is the fact that NT writers can refer to the OT people of God as the “church”: Stephen speaks of the gathered Israelites in the wilderness as “the assembly [ἐκκλησία] in the wilderness” (Acts 7:38). The writer to the Hebrews uses OT language to depict Jesus saying that he will sing praise to God: “in the assembly [ἐκκλησία] I will sing your praise” (2:12, citing Ps 22:22). When Christians gather together, the language the writer to the Hebrews uses to describe their assembly bursts with fulfilled typological references to the OT: the writer tells them, “[Y]ou have come to Mount Zion, to the city of the living God, the heavenly Jerusalem. You have come to thousands upon thousands of angels in joyful assembly, to the church [ἐκκλησία] of the firstborn … to Jesus the mediator of a new covenant, and to the sprinkled blood that speaks a better word than the blood of Abel” (12:22–24). The reference to Abel inevitably reminds the reader that Christians are “surrounded by … a great cloud of witnesses” (12:1)—namely, the faithful heroes from Abel through Enoch, Abraham, Sarah, Gideon, David, and all the rest of the OT figures (ch. 11). One cannot help but see some kind of profound continuity in the people of God.
(2) The issue is broader than merely terminological. When Jesus declares, in a thoroughly Jewish context, that he will build his church (ἐκκλησία, Matt 16:18), what he has in mind, according to this Gospel, includes Gentiles too (28:18–20). His instructions on how to exercise church [ἐκκλησία] discipline (18:15–20) show how he is willing to blur distinctions we tend to make: the local church (which must be in view in ch. 18) is the outcropping of the entire church (ch. 16), and clearly includes both Jews and Gentiles. They constitute Messiah’s assembly, Messiah’s church. Nowhere is the one-ness of Messiah’s people, Messiah’s church, more powerfully worked out than in Paul’s letter to the Ephesians. Jewish believers and Gentile believers have been made “one” by Jesus, who is our peace (Eph 2:14). At one time the Gentiles were alienated from God, “excluded from citizenship in Israel and foreigners to the covenants of the promise” (2:12), but now the two groups constitute “one new humanity” (2:15). Gentiles are “no longer foreigners and strangers, but fellow citizens with God’s people and also members of his household” (2:19). This is the church (ἐκκλησία) that Christ loved and for which he died (5:25). One recalls that in the olive tree metaphor (Romans 11), there is but one vine, with branches being broken off from that vine or grafted onto it.