Because the Jews and Christians where allowed to serve in the government.
Because of the weakness of non-states (ones that werent official, just groups of people who called themselves states), and European powers had strong econimies and a well organized government. Hope this was useful :P
Answer:
I think he is a killer and criminal person
They didn't. At the time that Jesus lived the Romans had very little dealings with him. In fact they didn't even know who he was. That's why when it came time to arrest Jesus they had to have someone (Judas) point him out. It was only a certain group of Jewish authorities who perceived Jesus as a threat and so acted against him.