I googled but got nowhere. Is there any truth in the quote? Did Barnette fabricate a story based on text written by a classical writer (Plutarch?).
Martha Barnette - Learn a New Word - F
fanatic
(as a noun.) Someone marked by extreme, zealous, or unreasoning enthusiasm.
(as an adjective) Fanatical.
Long ago in ancient Rome, a general named Sulla received some helpful military advice from the goddess Bellona. In gratitude, Sulla directed that a temple be built for her, and imported some priests and priestesses from Asia Minor to establish rituals in her honor.
And what wild rites they were! Dressed in black, these holy ones regularly worked themselves into a religious frenzy -- the highlight of which involved ripping off their robes and gashing themselves with two-headed axes, spattering their own blood upon bystanders.
According to Roman belief, the goddess of that temple herself inspired those fits of religious ecstasy. The Latin word for "temple" is fanum,and for that reason, the Romans referred to such religious zeal as fanaticus -- the source of our own fanatic.
(In fact, you don't see it often, but the English word fane is a poetic synonym for "temple.") All of these "temple" words are the linguistic kin of yet another familiar English term [profane].)
"A fanatic is one who can't change his mind and won't change the subject." — Winston Churchill
It's a little distorted -- there doesn't seem to be any basis for the bit about "Sulla received some helpful military advice from the goddess Bellona" -- but otherwise yes, it's basically solid. Fanaticus could mean either "pertaining to a temple" or "fanatical, enthusiastic" in classical Latin. The link that Barnette draws to Bellona and Sulla must come from the following inscription, a gravestone found at Rome, Corpus inscriptionum latinarum 6.2234 = Inscriptiones latinae selectae 4181a:
d(is) m(anibus) L(ucio) Cornelio Ianuario fanatico ab Isis Serapis ab aedem Bellonae Rufiliae v(ixit) a(nnos) XXII m(enses) XI d(ies) XXI fec(it) C(aius) Calidius Custos amico b(ene) m(erenti).
To the departed spirit of Lucius Cornelius Ianuarius, a fanaticus for the temple of Bellona Rufilia in (the area of) Isis Serapis; he lived 22 years, 11 months, and 21 days. Gaius Calidius Custos made this for his well-deserving friend.
To those who know Latin: yes, the inscription is ungrammatical. This temple of Bellona is for an imported god, Ma Bellona: "Bellona" is an interpretatio Romana for the Cappadocian god Ma. "Isis et Serapis" is an alternate name for the Augustan Regio III, i.e. identifying where the shrine of Bellona Rufilia was.
The purported link to Sulla is
The upshot is that this Lucius Cornelius Ianuarius is a relative of Sulla's. In a 1975 article, Robert Palmer makes a rather complicated argument (apologies if you don't have access) that the Sullas were responsible for building three shrines to Ma Bellona: the shrines of Bellona Rufilia; Bellona Capitolina, apparently built after a fire on the Capitoline in 82 BCE; and Bellona Pulvinensis, attested in ILS 4180 and 4181 on the same page as in the link above.
Fanaticus in the inscription quoted above simply means "temple-follower". However, Bellona's fanatici were known for their orgiastic rites and tendencies towards self-mutilation, so we start to see the word with the modern meaning "fanatic" starting with Cicero in the mid-1st century BCE. The word gets used with this meaning and with a specific link to Bellona in Juvenal, Satires 4.123-4:
non cedit Veiento, sed ut fanaticus oestro
percussus, Bellona, tuo diuinat et...
Veiento did not give in, but like a fanatic struck
by your arrow, Bellona, he also prophesied as follows:...