Epistula ad monacho1

Of Our Father among the Saints, Athanasius. To those practicing the solitary life and established in faith in God, beloved and most longed-for brothers in the Lord, greetings. I give thanks to the Lord, who granted you to believe in him, so that along with the saints you also may have eternal life. But since there are some who hold the opinions of Arius, going around the monasteries for no other reason than that, by coming to you and returning from us, they may deceive the simple-minded; and there are some who affirm that they do not hold the opinions of Arius, but who condescend and pray together with them—of necessity, at the urging of some most sincere brothers, I have hastened to write to you, so that, preserving the pious faith which the grace of God works in you in a pure and guileless manner, you may not give occasion for scandal to the brothers. For when some, seeing you who are faithful in Christ associating and communing with them, suspecting that such a thing is indifferent, will certainly fall into the mire of impiety. So that this may not happen, be willing, beloved, to shun those who openly hold the opinions of impiety, and to beware of those who think they do not hold the opinions of Arius but commune with the impious; and especially, those whose opinion we reject, it is fitting to flee from communion with them. But if someone pretends to confess the right faith but is seen to commune with those others, urge such a one to abstain from that custom; and if he promises, consider such a one as a brother.

If he persists obstinately, avoid such a person. For by conducting yourselves in this way, you will keep your faith pure; and those others, seeing you, will be benefited, fearing lest they be considered impious and of the same mind as those.