I have a question regarding the destruction of Jerusalem in 70 AD. Do we know if the disciple Christians fled to the mountains like Jesus advised or did they participate in the Jewish-Roman war?     Mark 13:14-15  14 “When you see ‘the abomination that causes desolation’ standing where it does not belong– let the reader understand– then let those who are in Judea flee to the mountains.

Answer:

The answer is yes, we do have a record of what happened with the church in AD 70 (or more accurately AD 69) from Eusebius.  He reports that when the Roman army under Vespasian came to Jerusalem the church heeded the advice of Jesus and left Jerusalem.  He gives us some further specifics, telling us that the majority of the Christians in Jerusalem escaped to the city of Pella which is in the region of the Decapolis, east of the Jordan River.  Here is the quote from Eusebius, as well as another church historian, Epiphanus from the late fourth century:

The people of the Church in Jerusalem were commanded by an oracle given by revelation before the war to those in the city who were worthy of it to depart and dwell in one of the cities of Perea which they called Pella. To it those who believed on Christ traveled from Jerusalem, so that when holy men had altogether deserted the royal capital of the Jews and the whole land of Judaea…”

— Eusebius, Church History 3, 5, 3

This heresy of the Nazoraeans exists in Beroea in the neighbourhood of Coele Syria and the Decapolis in the region of Pella and in Basanitis in the so-called Kokaba(Chochabe in Hebrew). From there it 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

Both accounts come from well after the events, so some are skeptical of the reports, but there is no evidence to the contrary, so I believe it is reasonable to accept Eusebius at his word, and to believe that the Christians did indeed escape to Pella.  Eusebius is generally reliable, especially about the big events, and this was surely one of the big events.John Oakes