Sadean does exist ... Christianos

Thanks for that valuable input, Bingley.

I confess I didn't know the Marquis de Sade had any "philosophical and literary ideas", at least, any worth reading. Oftimes we confuse character with erudition or creativity, but, of course, there is no necessary correspondence.

As a matter of fact, there is compelling evidence that a benign form of manic-depression [mania without the depression] may account for the entrepreneurial spirit and economic prowess of the United States, a country which was built by daring and adventurous immigrants from other countries. There is a newly published book on this subject. I will look for it and report back.

BTW your report on the origin of "Christian" does resolve what appears to me [at least] to be a conspicuous exception to the implicit, not explicit, general 'rule' guiding "ist" endings [that is, eponymic "ist" endings].

Thanks again.