"Keep yourselves from harmful plants which Jesus Christ does not raise because they were not planted by the Father. WHat I found among you was not schism but a sort of weeding out process. All those who belong to God and Jesus Christ are with the bishop. All those who repent and come back to the unity of the Church, these will also be God's that they may live according to Jesus Christ. 'Do not be deceived,' brothers, if anyone promotes schism, 'he will have no part in the Kingdom of God.' (1 Cor 6:8-10) If anyone follows an alien faith, he is not in agreement with the Passion of Christ. Be very careful to participate in a single Eucharist: for there is only one flesh of our Lord Jesus Christ and a single cup by which we are united in his blood, a single altar and a single bishop with the presbyters and deacons, my fellow servants. Whatever you do, do it God's way."
-St. Ignatius of Antioch, Letter to the Philadelphians.