Weeeeeell, I wouldn’t say that eunuchs were always associated with purity or with being men. Almost always, yes, but there was one big ancient world exception.
One of the tamer versions of the story of the goddess Cybele was that initially she had both male and female parts, but the gods cut off her male bits. These bits grew into a tree which impregnated a girl, and her son was Attis. Cybele fell in love with Attis and showed up at his wedding, and Attis went crazy and cut off his male bits, as did some of the male onlookers. (There are much much worse stories about Attis, though, where he’s an independent god. So this may be the Cybele religion taking over the Attis religion.)
The priests of the goddess Cybele (also called the Magna Mater) all had to castrate themselves publicly in order to join up. (On a holiday, in a crowd full of frenzy.) There were also Roman rumors that some priests didn’t join up voluntarily, but generally they did.
During most of Roman history, Roman citizens were either strictly prohibited to join up as priests, or were forbidden via a law forbidding castration. This created a situation where castration was regulated by Roman law, and in some provinces it was not permitted except by special permission of the governor. This came into play in Alexandria, when some over-enthusiastic Christian young man applied for permission under a literal interpretation of the “some castrate themselves” saying. (The governor said no.)
Later on, this Alexandrian story got associated with Origen, but that seems to be totally made up. (Especially since his shtick was anything but literal interpretation of Bible sayings. The entire Alexandrian School was like that. It was the guys over in Syria who were into literal and overly literal interpretation.)
Anyway… the priests of Cybele notoriously also dressed up in women’s clothes and wore women’s hairstyles (albeit special priestly versions, not the styles of the day in the country where they lived). Basically the idea was either of total submission to their goddess by trying to become like her, or that Cybele really hated men and liked to see them sacrifice and suffer, or that the priests of Cybele were masochistic pain and dance junkies.) They would dance around with musical instruments, cut or beat themselves, and go into ecstasy (or frenzy). Priests of Atargatis, a similar ecstatic religion from the same area of the world, did similar things, although Atargatis was associated with a lot of worse things, like cannibalism.
(And that’s why the religion of Atargatis got banned at one point, just like the Druids. And those naughty Christians, of course, because everybody knows they eat flesh and drink blood.)
Anyway… I really don’t see the priests of Cybele as any kind of desirable role model. They were creepy, and people feared them. The growth of their religion was seen as a sign that a lot of the Roman Empire had bad psychological issues.
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