Donatism it ain’t
One thing that refusing to take Communion with those who reject the traditional catholic teaching of the Church is not, is Donatism. Rather Not spells it out again very clearly:
Donatism arose over sacraments celebrated by those who were alleged to have cooperated in Diocletian’s persecution. Donatists insisted that such cooperation rendered these sacraments invalid, and that this taint of invalidity infected all but themselves, the true (donatist) church in North Africa. The contrary catholic doctrine of ex opere operato, famously championed by St Augustine and repeated in Article 26, held that the sins of the celebrant did not affect the validity of a sacrament. The Donatist controversy was therefore never a contest between truth and charity, but an argument over truth, pure and simple.
Donatism was not a difference over morality-no one in Christian antiquity, Catholic or Donatist, thought that cooperating with persecuting authorities was without moral significance-but an error about validity, an error that dissenters within and without the Episcopal Church have not made. No one has argued that the episcopal orders of the consecrators of Gene Robinson were subsequently rendered null and void by Gene Robinson’s sexual habits, but that these bishops have, by their doctrine, broken communion with the rest of us. We, on the other hand, are not simply asserting that homosex is wrong-we are insisting that the claim that homosex is morally neutral is itself a falsehood, an untruth, and we will not have communion with a lie. We are not breaking fellowship with sinners (we’d all be in a lot of trouble if we did), nor are we declaring anyone’s sacraments invalid. Rather, we are refusing communion with heretics, something which St Augustine, even in his most rabid anti-donatist diatribes, never confused, never lost sight of, and would never have condemned.