Was Christianity started to control the masses and dictate poltical agendas

[The Grand Nudger]

Are we trusting Tacticus here? He wrote that Nero scapegoated the Christians for the fire.

He didn't -quite- write that, and that's just one disputed account.  

I don't doubt the specific accounts we know are largely fabricated, but for the same reason I believe Jesus existed I believe there were martyrs that inspired others.

Sure, but the scale and timing is a bit of a non-starter.  The earliest account we have of christians, specifically, running afoul of the law it's two deaconesses (yeah, in the feminine) and the response was to let them off the hook if they paid their taxes and mouthed some words.  Whether or not they were jesusists yet isn't actually clear from that, even.

Large-spread persecution in the 300s. The oppression was fairly localized before that, though. In the same way the story of Jesus would have died without the apostles and the Gospels, the stories of many instances of persecution for a century were probably lost as well; one could argue, anyway.

.....that;s the story, but who's telling it. when were they telling it...and now we're referring to lost stories?  Trouble abounds.  

Whatever Wikipedia tells me it is

LOL.