Hadrian to Servianus, 134 CE (Quoted by Giles, Hebrew and Christian Records, vol. II, p86, 1877):
"Egypt, which you commended to me, my dearest Servianus, I have found to be wholly fickle and inconsistent, and continually wafted about by every breath of fame. The worshipers of Serapis (here) are called Christians, and those who are devoted to the god Serapis (I find), call themselves Bishops of Christ are, in fact, devotees of Serapis. There is no chief of the Jewish synagogue, no Samaritan, no Christian presbyter, who is not an astrologer, a soothsayer, or an anointer. Even the Patriarch himself, when he comes to Egypt, is forced by some to worship Serapis, by others to worship Christ. They are a folk most seditious, most deceitful, most given to injury; but their city is prosperous, rich, and fruitful, and in it no one is idle."
Admittedly this appears in the Historia Augusta which "In modern times most scholars read the work as a piece of deliberate mystification written much later than its purported date, however the fundamentalist view still has distinguished support. (...) The Historia Augusta is also, unfortunately, the principal Latin source for a century of Roman history. The historian must make use of it, but only with extreme circumspection and caution." (The Cambridge History of Classical Literature: Volume 2, Latin Literature, Part 5, The Later Principate, E. J. Kenney, Wendell Vernon Clausen, p43, 45, Cambridge University Press, 1983,ISBN 0521273714)