The following is a brief excerpt from the first chapter of The Apostolic Preaching and its Development by C.H. Dodd, who was one of the leading New Testament scholars of the 20th century. Dodd examines what was the earliest message that the New Testament church preached:
“It pleased God,” says Paul, “by the foolishness of the Preaching to save them that believe.” The word here translated “preaching,” kerygma, signifies not the action of the preacher, but that which he preaches, his “message,” as we sometimes say.
The New Testament writers draw a clear distinction between preaching and teaching. The distinction is preserved alike in Gospels, Acts, Epistles, and Apocalypse, and must be considered characteristic of early Christian usage in general. Teaching (didaskein) is in a large majority of cases ethical instruction. Occasionally it seems to include what we should call apologetic, that is, the reasoned commendation of Christianity to persons interested but not yet convinced. Sometimes, especially in the Johannine writings, it includes the exposition of theological doctrine. Preaching, on the other hand, is the public proclamation of Christianity to the non-Christian world. The verb keryssein properly means “to proclaim.” A keryx may be a town crier, an auctioneer, a herald, or anyone who lifts up his voice and claims public attention to some definite thing he has to announce. Much of our preaching in Church at the present day would not have been recognized by the early Christians as kerygma. It is teaching, or exhortation (paraklesis), or it is what they called homilia, that is, the more or less informal discussion of various aspects of Christian life and thought, addressed to a congregation already established in the faith.
The verb “to preach” frequently has for its object “the Gospel.” Indeed, the connection of ideas is so close that keryssein [preaching] by itself can be used as a virtual equivalent for evangelesthai, “to evangelize,” or “to preach the Gospel.” It would not be too much to say that wherever “preaching” is spoken of, it always carries with it the implication of “good tidings “ proclaimed.
For the early Church, then, to preach the Gospel was by no means the same thing as to deliver moral instruction or exhortation. While the Church was concerned to hand on the teaching of the Lord, it was not by this that it made converts. It was by kerygma, says Paul, not by didache [teaching], that it pleased God to save men.
We have to enquire how far it is possible to discover the actual content of the Gospel preached or proclaimed by the apostles.
First, we may place before us certain recurrent phrases which indicate in brief the subject of the preaching. In the Synoptic Gospels we read of “preaching the Kingdom of God,” whether the reference is to Jesus or to His followers. In the Pauline epistles we commonly read of “preaching Christ.” In the Acts of the Apostles both forms of expression are used. The apostles preach “Jesus” or “Christ,” or they preach “the Kingdom of God.” We may observe that in those parts of Acts where the writer speaks in the first person Paul himself is represented as “preaching the Kingdom of God.” We may therefore take it that a companion of Paul regarded his preaching as being just as much a proclamation of the Kingdom of God as was the preaching of the first disciples or of their Master, even though Paul does not himself speak of it in those terms.
Such expressions obviously need a good deal of expansion before we can form a clear idea of what it was that the apostles actually preached. We must examine our documents more closely.
For the rest of the chapter where he explores the actual content of apostolic preaching, analyzing the messages of Paul and Peter, as well as the Gospels and the rest of the New Testament canon go here.