False etymology ahead
Cretin as Christian is not the etymology of Cretin that I was taught. I have no data in support of this, but I was told it as fact.
Lesbian originally meant someone from the Isle of Lesbos, where Sappho the famous woman-loving woman poet lived, and thus "inhabitant of Lesbos" became synonymous with "dyke", even if most people on that island weren't what we call Lesbians. I have met a person from Lesbos, and he certainly wasn't a dyke.
I was taught that the word Cretin derived similarly from the inhabitants of Crete, where apparently indoor plumbing was an early innovation in Roman times, but unfortunately the material chosen to make the pipes was lead, resulting in an increase in the prevalence of congenital idiocy to such an extent that "inhabitant of Crete" became synonymous with "Idiot", and if some speculation is to be believed, contributed to The Decline and Fall of the Roman Empire. The real story about the Romans and Lead is over at Lead Poisoning and the Fall of the Roman Empire.
Ah well, it seems to have been one of those lies your parents tell you.
Anark point out that
Cretan not the same as
Cretin. True, but they are a lot closer in spelling and pronounciation than
Cretin and
Christian. And Lesbian is not the same as Lesbosian. Any more.
mblaise pointed out: I think
Anark's writeup got much of its data from http://www.takeourword.com/Issue027.html -- which seems pretty
authoritative to me.