Acts 20

 As Paul is trying to return to Jerusalem in time for Pentecost, he met witj the leaders of Ephesus in Miletus.  After again giving them instructions, he warns - 

"For I know this, that after my departing shall grievous wolves enter in among you, not sparing the flock.

30 Also of your own selves shall men arise, speaking perverse things, to draw away disciples after them"  Acts 20:29–30)

"And when he had thus spoken, he kneeled down, and prayed with them all.

37 And they all wept sore, and fell on Paul’s neck, and kissed him,

38 Sorrowing most of all for the words which he spake, that they should see his face no more. And they accompanied him unto the ship."  (Acts 20:36–38)

It seems apparent to me how difficult it would be all the converts to stay active when there was such distance between them with so little technology.