Epistle to the Philadelphians: Longer Version (Spurious) 4Avoid schismatics.

Keep yourselves, then, from those evil plants which Jesus Christ does not tend, but that wild beast, the destroyer of men, because they are not the planting of the Father, but the seed of the wicked one. Not that I have found any division among you do I write these things; but I arm you beforehand, as the children of God. For as many as are of Christ are also with the bishop; but as many as fall away from him, and embrace communion with the accursed, these shall be cut off along with them. For they are not Christ's husbandry, but the seed of the enemy, from whom may you ever be delivered by the prayers of the shepherd, that most faithful and gentle shepherd who presides over you. I therefore exhort you in the Lord to receive with all tenderness those that repent and return to the unity of the Church, that through your kindness and forbearance they may recover themselves out of the snare of the devil, and becoming worthy of Jesus Christ, may obtain eternal salvation in the kingdom of Christ. Brethren, be not deceived. If any man follows him that separates from the truth, he shall not inherit the kingdom of God; and if any man does not stand aloof from the preacher of falsehood, he shall be condemned to hell. For it is obligatory neither to separate from the godly, nor to associate with the ungodly. If any one walks according to a strange opinion, he is not of Christ, nor a partaker of His passion; but is a fox, a destroyer of the vineyard of Christ. Have no fellowship with such a man, lest ye perish along with him, even should he be thy father, thy son, thy brother, or a member of thy family. For says [the Scripture], "Thine eye shall not spare him." You ought therefore to "hate those that hate God, and to waste away [with grief] on account of His enemies." I do not mean that you should beat them or persecute them, as do the Gentiles "that know not the Lord and God;" but that you should regard them as your enemies, and separate yourselves from them, while yet you admonish them, and exhort them to repentance, if it may be they will hear, if it may be they will submit themselves. For our God is a lover of mankind, and "will have all men to be saved, and to come to the knowledge of the truth." Wherefore "He makes His sun to rise upon the evil and on the good, and sendeth rain on the just and on the unjust;" of whose kindness the Lord, wishing us also to be imitators, says, "Be ye perfect, even as also your Father that is in heaven is perfect."