Question: If someone asks me to anathematize Nestorius and the heretics with him, should I do this or not?
Response by John: That Nestorius and those heretics who follow him are under anathema, this is clear. But you should not hurry to anathematize anyone at all. For one who regards himself as sinful should mourn over one’s sins, and do nothing else. Neither, however, should you judge those who anathematize someone; for each person tests oneself.
Question: But if one thinks, as a result of this, that I believe the same as Nestorius, what should I tell him?
Response by John: Tell him: “Although it is clear that those people are worthy of their anathema, nevertheless I am more sinful than every other person and feel that, in judging another, I may condemn myself. Indeed, even if I anathematize Satan himself, if I am doing his works, then I am anathematizing myself.
“For, the Lord said: ‘If you love me, you will keep my commandments’ (Jn 14:15). And the Apostle says: ‘Whosoever does not love the Lord, let that person be under anathema’ (I Cor 16:22). Therefore, one who does not keep His commandments does not love Him; and one who does not love Him, is under anathema. So, then, how can such a person anathematize others?” Say these things to him; and if he persists in this, then for the sake of his conscience, just anathematize the heretic!