No, it is silly to state such a conspiracy theory (that followers were killed because their beliefs were true).
If we are to accept such a conspiracy theory, then we can apply the same to any other number of believers who have been killed for their beliefs, arguably, under the same guise as your own theory, to stop their beliefs.
If we are to accept that basic premise, that believers are killed because their beliefs are true, then you would have only to look at any other number of other competing beliefs: Judaism, Islam, Zoroastrianism, Paganism, Buddhism, etc.
If we maintain the viewpoint of Christianity, that Jesus is the son of the one true god, AND that believers are killed to stop a true message from getting across, we can conclude that if any of the above were killed for their beliefs, then yours is wrong. If yours is right, theirs is wrong.
Or more likely, they are all wrong.