The Historical Jesus

[Belacqua]

If it was obvious, no one would find it jarring. Anonymous, though, is another good term.

Points for using the secondary meaning of a little-used term, if that's what you were going for. Not that I have room to throw stones at someone for being pedantic. Carry on.

I had also never heard the word "unauthored" before. 

It's not in Merriam Webster or the OED. But of course the Internet has everything, so if you search it comes up as the second definition on Wiktionary plus some sites I'd never heard of. The first definition is always more like "not authored, without an author, unwritten." And that makes more sense to me, because "to author" means "to write," so "unauthored" would mean "unwritten." 

I'd find it more understandable in a sentence like, "Although George R.R. Martin planned a final volume in the series, it remained unauthored." Meaning that he never got around to writing it. Though even there, "unwritten" would be more normal.

Also my computer's spell check doesn't recognize the word -- it keeps trying to change it to "unauthorized."

But if someone likes the second, less obvious meaning I'm happy to play along. 

There is a danger that those terrible horrible Christian folks will misinterpret the word. They actually believed (before we smarter folks came along) that some texts had no author because they were given directly by God. More than written texts, painted icons were sometimes considered to have descended from heaven untouched by human hands. The Acheiropoieta icons played an important role in the debates between iconoclasts and iconodules. Depending on context, a possible English translation of Acheiropoieta could be "unauthored." So people who believe in this sort of thing would read "unauthored" to mean "arrived direct from God."