Psalms 55:12

"For if an enemy had upbraided me" [Psalm 55:12]. And indeed above he was "troubled in his exercise" by the voice of the enemy and by the tribulation of the sinner, perhaps being placed in that city, that proud city that was building a tower, which was "sunk," that divided might be the tongues: give heed to his inward groaning because of perils from false brethren. "For if an enemy had upbraided me, I would have undergone it assuredly, and if he that did hate me had over me spoken great words," that is, through pride had on me trampled, did magnify himself above me, did threaten me all in his power: "I would hide myself assuredly from him." From him that is abroad, you would hide yourself where? Amid those that are within. But now see whether anything else remains, but that thou seek solitude.

But what especially strengthens us in our desire for union with you is the account of your reverences' zeal for orthodoxy—the fact that neither by a vast number of treatises nor by subtlety of sophisms was your firmness of heart overcome, but that you recognized those who were making innovations contrary to the teachings of the apostles and did not consent to cover over in silence the harm done by them. Truly, we have found great grief among all those who are clinging to the peace of the Lord because of the manifold innovations of Apollinaris of Laodicea, who has grieved us so much more in that he seemed to belong to our party in the beginning. In fact, any suffering from an evident enemy, even if the pain is excessive, can somehow be borne by the one afflicted, as it is written: "For if my enemy had reviled me, I would verily have borne with it." But, to experience some hurt from one who is of like spirit and an intimate friend, this is most certainly hard to bear and holds no consolation. For, him whom we had expected to have as a fellow defender of the truth, him, I say, we have now found hindering in many places those who are being saved by perverting their minds and drawing them away from the right doctrine.

So one who does the will of God is his friend and is honored with this name. He who is of one mind with him, he too is his friend. For there is unity of mind in friends, and no one is more hateful than the person who injures friendship. Hence in the traitor the Lord found this the worst point on which to condemn his treachery, namely, that Judas gave no sign of gratitude and had mingled the poison of malice at the table of friendship. So he says, "It was you, a man of like mind, my guide and my acquaintance, who ever did take pleasant meals with me." That is: it could not be endured, for you did fall on him who granted grace to you. "For if my enemy had reproached me I could have borne it, and I would have hid myself from him who hated me." An enemy can be avoided; a friend cannot, if he desires to lay a plot. Let us guard against him to whom we do not entrust our plans; we cannot guard against him to whom we have already entrusted them. And so to demonstrate all the hatefulness of the sin he did not say, You, my servant, my apostle; but you, a man of like mind with me; that is, you are not my betrayer but your own, for you did betray a man of like mind with yourself.