3. Yes surely; while all of us are and are called Christians after Christ, Marcion broached a heresy a long time since and was cast out; and those who continued with him who ejected him remained Christians; but those who followed Marcion were called Christians no more, but henceforth Marcionites. Thus Valentinus also, and Basilides, and Manichæus, and Simon Magus, have imparted their own name to their followers; and some are accosted as Valentinians, or as Basilidians, or as Manichees, or as Simonians; and other, Cataphrygians from Phrygia, and from Novatus Novatians. So too Meletius, when ejected by Peter the Bishop and Martyr, called his party no longer Christians, but Meletians, and so in consequence when Alexander of blessed memory had cast out Arius, those who remained with Alexander, remained Christians; but those who went out with Arius, left the Saviour’s Name to us who were with Alexander, and as to them they were hence-forward denominated Arians. Behold then, after Alexander’s death too, those who communicate with his successor Athanasius, and those with whom the said Athanasius communicates, are instances of the same rule; none of them bear his name, nor is he named from them, but all in like manner, and as is usual, are called Christians. For though we have a succession of teachers and become their disciples, yet, because we are taught by them the things of Christ, we both are, and are called, Christians all the same. But those who follow the heretics, though they have innumerable successors in their heresy, yet anyhow bear the name of him who devised it. Thus, though Arius be dead, and many of his party have succeeded him, yet those who think with him, as being known from Arius, are called Arians. And, what is a remarkable evidence of this, those of the Greeks who even at this time come into the Church, on giving up the superstition of idols, take the name, not of their catechists, but of the Saviour, and begin to be called Christians instead of Greeks: while those of them who go off to the heretics, and again all who from the Church change to this heresy, abandon Christ’s name, and henceforth are called Arians, as no longer holding Christ’s faith, but having inherited Arius’s madness. (Athanasius, Discouse I Against the Arians I.III)
What more can I add? I wonder what our dear Athanasius would think of the Lutherans, Baptists, Wesleyans, Methodists, Presbyterians and the whole host of sects and denominations?