[to preach Christianity] meant [primarily to preach the Resurrection]

In the earliest days of Christianity[an ‘apostle’] was first and foremost a man /who claimed to be an eyewitness of the Resurrection. Only a few days after the Crucifixion /when two candidates were nominated /for the vacancy /created by the treachery of Judas,their qualification was that they had known Jesus /personally /both before and after His deathand could offer first-hand evidence of the Resurrection /in addressing the outer world (Acts 1:22).  A few days later [St Peter], preaching the first Christian sermon, makes the same claim—‘God raised Jesus, of which we all (we Christians) are witnesses’ (Acts 2:32).  In the first Letter to the Corinthians, St Paul bases his claim to apostleship on the same ground—‘Am I not an apostle? Have I not seen the Lord Jesus?’ (1:9). As this qualification suggests, [to preach Christianity] meant [primarily to preach the Resurrection. . . ]The Resurrection is the central theme /in every Christian sermon /reported in the Acts.  [The Resurrection, and its consequences], were the ‘gospel’ or good news //which the Christians brought:[what we call the ‘gospels’, the narratives of Our Lord’s life and death], were composed /later/for the benefit of those //who had already accepted the gospel.  They were in no sense the basis of Christianity: they were written for those already converted.  [The miracle of the Resurrection, and the theology of that miracle,] comes first:the biography comes /later as a comment on it. . .  [The first fact in the history of Christendom] is a number of people //who say () they have seen the Resurrection.  If they had died /without making anyone else believe this ‘gospel’no gospels would ever have been written. From Miracles Compiled in A Year with C.S. Lewis