If the heretics had never started with the violence, then even if they had used all the ways they had ways they could to lure the people by preaching, even if they had thereby done what Luther does now and Mohammed did before – bring into vogue opinions pleasing to the people, giving them licence for licentiousness – yet if they had left violence alone, good Christian people would perhaps all the way up to this day have used less violence towards them than they do now. And yet heresy well deserves to be punished as severely as any other sin, since there is no sin that more offends God. However, as long as they refrained from violence, there was little violence done to them. And certainly though God is able against all persecution to preserve and increase his faith among the people, as he did in the beginning, for all the persecution inflicted by the pagans and the Jews, that is still no reason to expect Christian princes to allow the Catholic Christian people to be oppressed by Turks or by heretics worse than Turks.
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We read that in the time of Saint Augustine, the great theologian of the Church, the heretics in Africa called the Donatists resorted to force and violence, robbing, beating, torturing and killing those whom they seized from the true Christian flock, as the Lutherans have done in Germany. For putting a stop to which , that holy man St Augustine, who had for a long time with great patience borne and endured their malice, only writing and preaching in refutation of their errors, and not only had done them no temporal harm but also had hindered and opposed others would have done it, did yet at last, for the peace of good people, both permit and exhort Count Boniface and others to supress them with force and threaten them with corporeal punishment.
… For here you shall understand that it is not the clergy who endeavour to have them punished by death. It may well be, since we are all human beings and not angels, that some of them may sometimes have too hot a head, or an injudicious zeal, or perhaps, an irascible and cruel heart, by which they may offend God in the very same deed by which they would otherwise gain great merit. But certainly what the Church law on this calls for is good, reasonable, compassionate, and charitable, and in no way desirous of the death of anyone. …