1 As there is one body of the Catholic Church, and a command is given us in the sacred Scriptures to preserve the bond of unity and peace, it is agreeable thereto that we should write and signify to one another whatever is done by each of us individually; so that whether one member suffer or rejoice, we may either suffer or rejoice with one another. Now there are gone forth in this diocese, at this time, certain lawless men, enemies of Christ, teaching an apostasy, which one may justly suspect and designate as a forerunner of Antichrist.
I was desirous to pass such a matter by without notice, in the hope that perhaps the evil would spend itself among its supporters, and not extend to other places to defile the ears of the simple. But seeing that Eusebius, now of Nicomedia, who thinks that the government of the Church rests with him, because retribution has not come upon him for his desertion of Berytus, when he had cast an eye of desire on the Church of the Nicomedians, begins to support these apostates, and has taken upon him to write letters every where in their behalf, if by any means he may draw in certain ignorant persons to this most base and antichristian heresy; I am therefore constrained, knowing what is written in the law, no longer to hold my peace, but to make it known to you all; that you may understand who the apostates are, and the cavils which their heresy has adopted, and that, should Eusebius write to you, you may pay no attention to him, for he now desires by means of these men to exhibit anew his old malevolence, which has so long been concealed, pretending to write in their favour, while in truth it clearly appears, that he does it to forward his own interests.
Source: Deposition of Arius (New Advent)