Directly means "I lack knowledge."

Gnosticism relates to knowledge. Theism to belief. Agnostic doesn't mean "in the middle," It means "lacking knowledge." Ask yourself "Is there a god?" If the answer is anything other than "yes," then congratulations, you're an atheist. "Maybe" is not "yes." You'd be an agnostic atheist.

Anyway, if there was a god, he would know exactly what it would take to make you believe. Until that happens, you don't know for sure what that might be.

Also if you did indeed witness a "miracle," no matter the definition (exceedingly rare event etc), you do not say "I guess (insert the version of god I believe in) did it." Instead, you say "Wow I don't have an explanation for why that happened, lets investigate." So your argument is on the right track.

Also, there's a chapter of Bleach titled Debating Life from God's Viewpoint, which has a fantastic quote: "Only my power is absolute. Everything else is tiny and insignificant. In my cavernous eyes, your lives and those of ants are exactly the same."