Acts 12:25

And Barnabas and Saul returned from Jerusalem, when they had fulfilled their ministrations, taking with them John whose surname was Mark.

This is a reference to the same journey mentioned in Acts 11:30; but here is the additional word that John Mark accompanied them. See under Acts 11:30.

Fulfilled their ministration ... This means that they accomplished the purpose of their journey, delivering to the elders in Jerusalem the bounty provided by the generosity of the Christians to relieve the victims of that famine in the reign of Claudius. The year 44 A.D. was the time of these events, this being one of the points at which Acts touches firm dates in the secular history of the first century.

John whose surname was Mark ... Just as Stephen's martyrdom was made the occasion, by Luke, of mentioning Saul of Tarsus, here is the introduction of another character who would figure prominently in Luke's subsequent chapters of Acts, John Mark. If Luke had ever seen Mark's gospel, this would have been a "must" occasion for his mentioning it; and therefore the silence of Luke here concerning the gospel of Mark is a strong suggestion that he knew nothing of it.

With the conclusion of this chapter, Luke had set the stage for the world-wide program of evangelism among the Gentiles; and he would at once move to the narrative of Paul's first missionary journey.