This short thread addresses the often-repeated legend that Christians fled Jerusalem to Pella and escaped the destruction of Jerusalem. The legend is based upon two 4th century comments.
The whole body, however, of the Church at Jerusalem, having been commanded by a divine revelation given to men of approved piety there before the war, removed from the city to a certain town beyond the Jordan called Pella. Here, those who believed in Christ removed from Jerusalem as if holy men had abandoned the royal city itself and the whole land of Judea.
— Eusebius, Church History 3, 5, 3
So Aquila (Translator of Old Greek LXX) while he was in Jerusalem, also saw (the disciples of the disciples of) the apostles flourishing in the faith and working great signs, healings, and other miracles. For they were such as had come back from the city of Pella to Jerusalem and were living there and teaching. For when the city was about to be taken and destroyed by the Romans, it was revealed in advance to all the disciples by an angel of God that they should remove from the city, as it was going to be completely destroyed. They sojourned as emigrants in Pella, the city above mentioned in Transjordania. And this city is said to be of the Decapolis.
— Epiphanius, On Weights and Measures 15
In these two passages Christians were said to have been given revelations or a message from an angel telling them to leave for Pella. A second passage allegedly from Epiphanius however reads:
This heresy of the Nazoreans... took its beginning after the exodus from Jerusalem when all the disciples went to live in Pella because Christ had told them to leave Jerusalem and to go away since it would undergo a siege. Because of this advice they lived in Perea after having moved to that place, as I said.
— Epiphanius, Panarion 29,7,7-8
It would seem odd for the legend of a revelation or an angel messenger to have arisen after the version that attributed it to Jesus, suggesting the legend connecting the existence of Christians in Pella with the Gospel is a later invention.
In fact, he first quote from Epiphanius forms part of an explanation for an apparent contradiction with the belief that Christians had left Jerusalem with the legend that they were in Jerusalem in Hadrian's time still doing miracles......they had somehow and for some reason returned to live in a burnt-out city! The record shows however that when Hadrian arrived (129/30) and determined to rebuild the city as a Roman outpost, Jews (and Jewish Christians) were still forbidden entry on penalty of death. That is after all what inspired the Bar Kochba revolt a few years later and the eventual horrific Roman victory. This demonstrates the lack of historical credibility of many early Christian writings. Distanced by hundreds of years and living at a time when the Jews were again allowed to return (313CE), Epiphanius was unaware of the impossibility of Jerusalem Christians returning and thriving at the time of Hadrian.
As an interesting side note, the earlier Greek form of Weights and Measures simply mentions "apostles'" thriving doing all kinds of miracles, whereas the Syriac form adds 'disciples of disciples of' apostles. Clearly, we are seeing a solidification of a more exclusive use of the term 'apostle'.