We are not in any great perturbation or alarm about the persecutions we suffer from the ignorance of men; for we have attached ourselves to this sect, fully accepting the terms of its covenant, so that, as men whose very lives are not their own, we engage in these conflicts, our desire being to obtain God's promised rewards, and our dread lest the woes with which He threatens an unchristian life should overtake us. Hence we shrink not from the grapple with your utmost rage, coming even forth of our own accord to the contest; and condemnation gives us more pleasure than acquittal.
We have sent, therefore, this tract to you in no alarm about ourselves, but in much concern for you and for all our enemies, to say nothing of our friends. For our religion commands us to love even our enemies, and to pray for those who persecute us, aiming at a perfection all its own, and seeking in its disciples something of a higher type than the commonplace goodness of the world. For all love those who love them; it is peculiar to Christians alone to love those that hate them. Therefore mourning over your ignorance, and compassionating human error, and looking on to that future of which every day shows threatening signs, necessity is laid on us to come forth in this way also, that we may set before you the truths you will not listen to openly.
Source: To Scapula (New Advent)