These cannibal lunatics are going to destroy the Empire!

Explanation: Early Roman interactions with Christianity were highly suspicious - noted is the persistent rumor that Christians were incestuous cannibals, which is why they always insisted on meeting in secret! What dangerous cultists!

Of course, in reality, the whole ‘eating the body and drinking the blood of God in the form of man’ is just a convoluted spiritual thing, not a confession to actual cannibalism, and likewise, calling each other ‘brother’ and ‘sister’ an expression of spiritual solidarity, not literally asserting that the boy you’re canoodling with is your actual brother. This was recognized early on by Roman authorities like the governor Pliny the Younger and the Emperor Trajan, who noted that the only crime of the Christians was meeting in secret and being superstitious.

Nevertheless, the rumors never fully stopped - bizarre folks, these Christians! Can’t trust ‘em!