Ante-Nicene Fathers Volume 5
Cyprian: Epistles XXXVII-XXXIX
These Epistles deal with the problem of the faction created by one Felicissimus. It's a little unclear what the exact nature of the problem is, but it appears that Felicissimus is doing something untoward with church funds, and possibly committing sexual sins ("the crime also of adultery," though this may be a reference to spiritual adultery rather than that of seducing someone's spouse). Cyprian notifies the other elders that Felicissimus has been excommunicated, and that anyone who follows him or continues to associated with him should be excommunicated as well. This apparently includes some confessors and some of Cyprian's fellow exiles and a handful of elders. At least a part of the sin of these elders was the creation of a new way of handling the lapsed, perhaps even by refusing to readmit them to communion at all. The sin of these elders specifically was acting unilaterally when it had already been agreed "that no novelty should be introduced in respect of the case of the lapsed unless we all assembled into one place, and our counsels being compared, should decide upon a moderate sentence, tempered alike with discipline and with mercy."
In a moving passage, Cyprian tells his congregation how much he misses them and hates being away. This in turn highlights the sin of these elders who would tear apart the congregation. The church ought to be unified, since "There is one God, and Christ is one, and there is one church, and one chair founded upon the rock by the word of the Lord." We must not divide Christians from Christ: "let no one snatch you, Christians, from the Gospel of Christ, let no one take sons of the Church away from the Church." We must specifically reject anyone who tries to insert their own traditions into the life of the church, and in doing so make it less merciful (again, this relates to the lapsed--"let one downfall be sufficient for the lapsed; let no one by his fraud hurl down those who wish to rise."). We must all pray together as a church body for the restoration of the lost while avoiding the traps set by sin and the devil for God's people.