Archaic Christianity

There are a number of things one must do to become a great Christian thinker. One must study, be godly, and be able to communicate. But those criteria are easy to come up with, despite being hard to fulfill. Another criterion, much less appreciated, is the ability to insult the idiots those of inferior thinking that you may be dealing with at the moment. The best historical Christian writer in my experience is Calvin. Luther could do it too, but Calvin was better. I still haven't found anyone who could beat Calvin's statement, (and this is not an exact quote) "Pighius, you are so full of hot air I am surprised that you do not fart constantly" in his Bondage and Liberation of the Will. Of course Paul had no problem telling the Galatians that they were stupid, but that zinger is just a little bland :) Here's one from Irenaeus (Against Heresies, 8.1). I quote the paragraph in full so you can see just how bad the person is whom he is describing. The colorful characterization is at the end.

But there is another among these heretics, Marcus by name, who boasts himself as having improved upon his master. He is a perfect adept in magical impostures, and by this means drawing away a great number of men, and not a few women, he has induced them to join themselves to him, as to one who is possessed of the greatest knowledge and perfection, and who has received the highest power from the invisible and ineffable regions above. Thus it appears as if he really were the precursor of Antichrist. For, joining the buffooneries of Anaxilaus to the craftiness of the magi, as they are called, he is regarded by his senseless and cracked-brain followers as working miracles by these means.

I need to get the Latin or Greek words behind "cracked-brain". Anyway, all of this is only sorta tongue-in-cheek. A number of the great writers of the past have not been reticent to heap scorn on heretics. I wonder what the proper Christian response to this is. Obviously this kind of criticism would be inappropriate for someone considered a brother (unless it were a joke, perhaps). Any thoughts?