Pope St. Gelasius Against Communion With Heretics

Pope St. Gelasius, Letter 27 To The Bishops Of The East (AD 492-496): “Nor is there any doubt that, just as in each and every heresy (a fact that needs to be repeated without ceasing, because no Christian doubts that it is unwavering) all accomplices, followers, and those in communion with a crookedness that has been condemned once and for all, are adjudged to a matching fate… let nobody offer the excuse that he did not hold communion with someone or other who is perhaps more obviously heretical, or he will be regarded as being in communion with a heretic. For what help is it to him if he does not hold communion with him and is nevertheless joined in communion with those who are not hostile to communion with him? But if he was in communion with none of them or is not in any sort of communion [with such heretics], he will be of the sincere, Catholic, and apostolic communion and faith. Otherwise, there is no way that he could avoid the compound infection of that indiscriminate involvement… But this involvement [in communion with heretics] is thought by the Greeks, among whom there is no distinction between true and false, to be an easy matter and without blame, and because they want to be in communion with all reprobates they are shown not to stand firm in any rectitude.”