This should probably be split off.
There are many (partially conflicting) versions of what exactly made the christians troublesome for Rome. A version I've heard many times is that they would not worship the Emperor (because the Bible says they shalt not have other gods, etc.)
One theory I find particularily interesting is that they were simply distasteful to the romans. Other religions could be tolerated, but christians were just... blarg... - if you listen to fundamentalist christian right extremists in the USA today, you can very much share that sentiment.
But anyways, this should probably be split off as it's derailing the main topic.