How exactly is he a terrorist? The guy came and said 'love your enemies', healed a bunch of people, fed people advocated for human rights, suggested the rich take care of the poor and then got strung up and executed on false charges in the most graphic and painful way possible.
Exactly how does that define him as a terrorist? Serious question.
The book answers this quite well. Our main source of 'evidence' regarding Jesus as an individual was written by his followers and as a result, is always going to cast him in a positive light compared to how he might have been portrayed by the Romans prior to their acceptance of his religion.
Pontius Pilate as a historical figure showed no evidence of
ever being the kind of guy who would let the people choose who to execute, for example. This was likely something the Romans had changed years later to portray them in a better light and to cast the Jews in a worse light.
Jesus was a Jewish freedom fighter existing in a Roman controlled state that was at the time putting down similar religious figures with brutality. His story is the best known for obvious reasons, but he was not the only Jew fighting for Jewish rights or preaching a new angle on the religion. He was just the one whose followers told his story loudest and most widely.
Whether or not he was the actual Son of God is an entirely different story, but at the time he'd have been viewed as a terrorist. He may have preached positive messages, but he also preached it at odds with the Roman occupation and at odds with the existing Jewish hierarchy.
And let's not forget, he did use violence on at least one occasion as documented in the Bible. He tore through a temple throwing market stalls aside and raving at those who ran them.
