IV. The heretics must be forced to give up their usurpations and left to the judgment of God.
But we do not refuse the assistance of our ministry for the instruction of our little ones, who after being fed with milk desire to be satisfied with more solid food: and as we do not scorn the simple folk, so we will have no dealings with rebel heretics, remembering the Lord's command, who says, “Give not that which is holy to the dogs, nor cast your pearls before swine.” Surely it is altogether unworthy and unjust to admit to freedom of discussion men whom the Holy Spirit describes in the words of the prophet, “the sons of the stranger have lied unto me.”
For even though they resist not the Gospel, yet they have shown themselves to be of those of whom it is written “they profess that they know God but by their deeds they deny Him,” while the blood of just Abel still cries against wicked Cain, who being rebuked by the Lord did not set quietly about his repentance but burst forth into murder. Whose punishment we wish to be reserved for the Lord's judgment in such a way that, unprincipled plunderer and blood-thirsty murderer as he is, he may be thrown back upon himself and relinquish what is ours.
We pray you also not to suffer the lamentable captivity of the holy church of Alexandria to be any further prolonged, which by the help of your faith and Justice ought to be restored to its liberty, that through all the cities of Egypt the dignity of the Fathers and their priestly rights may be restored. Dated 21st of March in the consulship of Leo and Majorian Augusti (458).
Source: Letters (New Advent)