“agnostic (n.)
1870, “one who professes that the existence of a First Cause and the essential nature of things are not and cannot be known” [Klein]; coined by T.H. Huxley (1825-1895), supposedly in September 1869, from Greek agnostos “unknown, unknowable,” from a- “not” + gnostos “(to be) known”
http://www.etymonline.com/index.php?term=agnostic
ignoramus (n.)
1570s, from an Anglo-French legal term (early 15c.), from Latin ignoramus “we do not know,” first person present indicative of ignorare “not to know” (see ignorant). The legal term was one a grand jury could write on a bill when it considered the prosecution’s evidence insufficient. Sense of “ignorant person” came from the title role of George Ruggle’s 1615 play satirizing the ignorance of common lawyers.
http://www.etymonline.com/index.php?allowed_in_frame=0&search=ignoramus&searchmode=none
“AGNOSTIC” sounds so much more sophisticated than “IGNORAMUS”, though the meaning is the same (less your ‘nuances’).
Absolutely correct and you can toss the utterly illogical atheists in there too.