The early church had barely reached escape velocity when Rome leveled Jerusalem, by then all the Apostles had been martyred save John. It must have been a time of great uncertainty.

In a way, the sacking of Jerusalem aided the young church. At that time the most prevalent heresies were Judaizers/legalism. Even Peter had fallen into bad practices which Paul had to confront him about (Gal 2, 50AD)

Temple Judaism was completely annihilated after the siege of 70AD. The temple destroyed, over a million dead, and the gem of the Hebrews, Jerusalem, became a place for wild jackals.

Judaism (through the Pharisees and Sadducees) found itself in a position where it was no longer able to exert its influence or persecute a young impressionable church and was left to restructure itself, from its ashes was born rabbinic/talmudic Judaism i.e. not the faith of Abraham which continued with the early church (which were jew and gentile alike) in an unbroken faith line.

The Jews had until 70Ad to recognize that Jesus was the Messiah. If temple Judaism had survived then, one could make the argument that there would be a restoration, after all Jesus was the only missing piece. That is not the faith of Jews today. God gave his original people 38 years to jump on to the covenant of grace. (Hebrews 8:13) He didn't let 2000 years' worth of 'His people' die in sin (Luke 21:20-24) That's not what a merciful God does especially when He said that generation would see its end (Matthew 24:34)

The loss of life was less on the Christian side, many were saved because the Holy Spirit led them out of harm's way. Study the flight to Pella.