What price a single letter. The 'christianos' reference in a passage from the earliest extant version of Tacitus' Annals has for so long, for believers, served as a singularly vital piece of 'proof' for a historical Jesus that can be invoked and relied upon. It's cited everywhere, by most academic publications, even ones you'd think should know better.
Of course, the Bible and related history books over the ages are so full of interpolations and deletions and forgeries and manipulations and alterations that, without discoveries such as the Dead Sea Scrolls or other original papyrological documents, it's extremely challenging to attempt to unravel who wrote what and when with any degree of scientific certitude. In fact Tacitus' 'torched Christians' passage may be entirely fake, his later one-sentence background reference to 'Christus' most probably is an interpolation, based on contextual and inexplicably erroneous factual elements contained therein. What you can be sure about is the ruthless intent to perpetuate beliefs in these fables over the centuries leading to today and beyond. The intent to make believe mythology as real history as a means of exercising power and influence.
In 2009, Erik Zara made a fascinating reinvestigation of the Tacitus reference where you can actually see exactly how the original 'chrestianos' (= the good) was worked over and by whom. Pious forgery at work.