Part 18: The Wizard of Oz further talks about the rise of Christianity.The impression that I've always gotten is that belief in the Greek pantheon was rather weak, and had more to do with enforcing social standards and avoiding bad luck. Plus it was effective - if an augury goes your way you get a morale boost, and if it is an ill omen or you don't do it then morale would be really harmed. With the evangelical religions, so long as you have faith then God's on your side. And if you die horribly or lose all your money anyway, you won't necessarily be seen as a bad person who angered the gods, since you could still have gone to heaven.
I think the books helped too. Instead of a fractious array of religions with different features over time and space, you had a whole bunch of people from all over the place who believed the same thing. That made it much easier to spread and minimize integration into pre-existing religions. Still, it was by no means consistent - Islam destroyed the Arabic animist religions but was modified by Arabic social standards, particularly treatment of women.
And yeah, Socrates was definitely a hit job. He insulted powerful people, they gave him an opportunity to apologize and prove he's not a danger to the social order, he blathered on instead, and so they killed him. It was more complex than that, but that's the general gist as I understand it.