4 Certainly an excellent and lawful tradition is set before us by the teaching of our brother Stephen, which may afford us a suitable authority! For in the same place of his epistle he has added and continued: “Since those who are specially heretics do not baptize those who come to them from one another, but only receive them to communion.” To this point of evil has the Church of God and spouse of Christ been developed, that she follows the examples of heretics; that for the purpose of celebrating the celestial sacraments, light should borrow her discipline from darkness, and Christians should do that which antichrists do.
But what is that blindness of soul, what is that degradation of faith, to refuse to recognise the unity which comes from God the Father, and from the tradition of Jesus Christ the Lord and our God! For if the Church is not with heretics, therefore, because it is one, and cannot be divided; and if thus the Holy Spirit is not there, because He is one, and cannot be among profane persons, and those who are without; certainly also baptism, which consists in the same unity, cannot be among heretics, because it can neither be separated from the Church nor from the Holy Spirit.
Source: The Epistles of Cyprian (New Advent)