1. The ancients primarily gave the name of fanatici to those who uttered oracular announcements, or exhibited wild antics and gestures under the (supposed) inspiration of some divinity whose temples (fana) they frequented. The heathen vates, who pretended to prophesy under the guidance of an indwelling spirit (δαίμων), was called by the Greek writers ἔνθεος, and by the Latinsfanaticus (see Suidas, s.v. ἔνθους; Bingham, Orig. Ecclesiastes 16, 5:4). Thence the name was transferred to persons actuated by a frantic zeal in religion.
2. The word is sometimes improperly used to stigmatize such Christians as are "zealously affected in a good thing" (Ga 4:18). Its only legitimate application is to such as add to enthusiasm and zeal for the cause which they believe to be the cause of truth a hatred of those who are opposed to them, whether in politics, philosophy, or religion. Isaac Taylor, speaking of religious fanaticism, remarks that, "after rejecting from account that opprobious sense of the word fanaticism which the virulent calumniator of religion and of the religious assigns to it, it will to found, as we believe, that the elementary idea attaching to the term in its manifold application is that of fictitious fervor in religion, rendered turbulent, morose, or rancorous by junction with some one or more of the unsocial emotions. Or, if a definition as brief as possible were demanded, we should say that fanaticism is enthusiasm inflamed by hatred." He classifies the chief varieties of fanaticism "under four designations, of which the first will comprehend all instances wherein malignant religious sentiments turn inward upon the unhappy subject of them; to the second class will belong that more virulent sort of fanaticism which looks abroad for its victims; the third embraces the combination of intemperate religious zeal with military sentiments, or with national pride and the love of power; to the fourth class must be reserved all instances of the more intellectual kind, and which stand connected with opinion and dogma. Our first sort, then, is austere, the second cruel, the third ambitious, and the fourth factious.' Or, for the purpose of fixing a characteristic mark upon each of our classes as above named, let it be permitted us to entitle them as follows — namely, the first, the fanaticism of the scourge, or of personal infliction; the second, the fanaticism of the brand, or of immolation and cruelty; the third, the fanaticism of the banner, or of ambition and conquest; and the fourth, the fanaticism of the symbol, or of creeds, dogmatism, and ecclesiastical virulence" (Fanaticism, Neew York, 1834, 12mo, page 62).
The fanatic begins by rejecting the light of reason to abandon himself to the dictates of his fancy. He generally adopts some single and exclusive idea, which destroys the proper balance of his mind. This absorbing idea may have a germ of truth in it, but the fanatic will not recognize it, if in another form, in others: he cannot admit that truth which has taken a certain shape for him may have taken another in the eye of his neighbor without ceasing to be the truth. He thus becomes exclusive, malevolent, and prone to persecue tion. The hatred of blood relations is more intense and fierce than that between strangers, and so the fat. natic is all the more fierce and tyrannical against others in proportions as their views approach, his own, without being identically the same. He will undergo any suffering rather than abate one jot of his claims, or retreat one step forathe sake of charity and union. He prefers darkness to light, the letter to the spirit, hatred to love, the wildness of passion to the calmness of inquiry. Fanaticism may show itself in all the relations of life, but its special field is found in politics and religion; and it becomes most dangerous when the two are combined. Being entirely one-sided, it is yet liable to go in the most opposite directions, and then goes all lengths. Thus we have in politics fanatics of peace, who want peace at any cost, and under all circumstances; fanatics of unrest, who believe only in the overthrow of existing institutions; fanatics of progress, who think anything good if it is only new; and fanatics of the past, or conservatives, who wish to hold fast whatever is, no matter how bad it is; fanatics of liberty, who, however, require others. to view liberty in the same light as they do, or else deny it to them; and fanatics of despotism, who would wish all hearts to beat in unison, like so many well- reagulated clocks. We find cosmopolitan fanatics, who glory in reviling their own country, and patriotic fanatics, who consider alil other nations but their own as barbarians; and heathens; fanatics of rationalism, who consider every opponent a blockhead, and fanatics of orthodoxy, who think the pope requires only might to make him perfect, and who pray for the re- establishment of the Inquisition and the stake. Fanaticism has left especially sad records of its excesses in the religious history of the world, not only among the heathen in India, the Moslems and the Jews, but also among Christians. It caused the bloody encounters of the monks of Constantinople at the time of the controversy between the Eutychians and the Nestorians. It envenomed the quarrels of the Montanists and the Donatists. It persecuted the Jews in the Middle Ages. It organized the Inquisition, developed the method of the cogite intrare (Lu 14:23), and invented a new sense for the words in Tit 3:10 (hareticum de vita!); it instigated the crusade against the Albigenses, who when they were indiscriminately massacred, were comforted with the assurance that "the Lord would know his own;" it aimed the dagger in the hands of Ravaillac against the breast of his king; it inspired the Te Deum of Gregory XIII as a thanksgiving for the massacre of St. Bartholomew's. In the Protestant world we find fanaticism in the Anabaptists of Munster, in the Crypto- calvinistic troubles, and in the wars of the Cavaliers and Roundheads of England (Beck, in Herzog, Real-Encyklop. 4:327 sq.). "Fanaticism is the most incurable of all mental diseases, because in all its forms — religious, philosophical, or political — it is distinguished by a sort of mad contempt for experience, which alone can correct errors of practical judgments" (Mackintosh, Works, London, 1851, 2:671). See also Stillingfleet, Works, 5:19, 92, 130; Fletcher, Works (N.Y. ed.), 4:233 sq.