Agnostically

a person who holds that the existence of the ultimate cause, as God, and the essential nature of things are unknown and unknowable, or that human knowledge is limited to experience.
Synonyms: disbeliever, nonbeliever, unbeliever; doubter, skeptic, secularist, empiricist; heathen, heretic, infidel, pagan.
a person who denies or doubts the possibility of ultimate knowledge in some area of study.
a person who holds neither of two opposing positions on a topic:
Socrates was an agnostic on the subject of immortality.
of or relating to agnostics or their doctrines, attitudes, or beliefs.
asserting the uncertainty of all claims to knowledge.
holding neither of two opposing positions:
If you take an agnostic view of technology, then it becomes clear that your decisions to implement one solution or another should be driven by need.
Historical Examples

“He has been so unusually amiable,” agnostically said Justine.
A Fascinating Traitor Richard Henry Savage

noun
a person who holds that knowledge of a Supreme Being, ultimate cause, etc, is impossible Compare atheist, theist
a person who claims, with respect to any particular question, that the answer cannot be known with certainty
adjective
of or relating to agnostics
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” (see gnostic). Sometimes said to be a reference to Paul’s mention of the altar to “the Unknown God,” but according to Huxley it was coined with reference to the early Church movement known as Gnosticism (see Gnostic).

I … invented what I conceived to be the appropriate title of ‘agnostic,’ … antithetic to the ‘Gnostic’ of Church history who professed to know so much about the very things of which I was ignorant. [T.H. Huxley, “Science and Christian Tradition,” 1889]

The adjective is first recorded 1870.