How did Judaism flourish throughout the world even though Jews were
exiled and living in various places?
As persecutions forced the Jews to move to various countries, they brought their religion with them. Converts weren't actively sought, but there were some non-Jews who converted, including large numbers in a couple of instances. As Israel has only survived by the grace of God, God has to be listed as the number 1 reason Judaism survived and spread. As the Judges and Prophets spoke for God, the Spirit of God has to be the second reason. As it took faith to follow God, the Judges and Prophets of the Hebrew scripture have to be the third reason. Emagidson can't have it both ways. You can't say we have to longest culture and complain about outside threats. The reason the Jews have the oldest culture is because they have handled the outside threats that have wiped out the other cultures. One such time that Judaism was threaten was the destruction of the 2nd Temple. Israelites living in Israel did not know life where Rome's political and religion ruled the day. Some will say that Rome didn't rule Jewish religion but the High Priest was chosen by Rome rather than according to the mandate laid out by the Torah. And the Temple was often referred to as Herod's Temple which would not have been the preferred Jewish name. After a failed revolt, Jerusalem was under siege. It was the hostility between Jewish groups that lead to the Jews burning their own food supply. Stravation followed. When Jerusalem fell, the Temple was destroyed, many men were killed, and many women were raped. It was the creativity of the leadership that overcame the sure Jewish destruction. Had Judaism not shifted from being God centered to being cultured centered, this would have destroyed Israel like it was intended to do. Because of the shift, God no longer has to speak or act as was needed as when the Torah was being observed. There is no need for prophets either. With out a need for God or prophet, there became a need to have an scripture-like text which allowed the many diverse groups of Judaism to co-exist as Jews. Figuritively speaking, out from the flames of a burn Jerusalem, out pops a golden Talmud which meets all the needs of the people which the Torah could not. So today, there is no need for a Temple, priest or sacrifice as the Torah commands.