To the THEIST QUESTION one either AGREES (says yes there is creator) or says something OTHER THAN YES (maybe, no, or idk if there is a creator.)
So the "agnostic" that you have described does not exist.
1. Ask a Christian the theist proposition, and the Christian may say "Well I don't know for sure, but I have faith in the lord almighty..."
In which case THE CHRISTIAN in 1 is actually "an agnostic" as you describe.
Few people understand what agnosticism means. Even the pope is "agnostic" because he would NOT BE ARROGANT ENOUGH to say "I am omniscient and have divine knowledge of my future. I cannot be wrong." He would be HUMBLE (as prescribed even by Christianity) and say "I the humble man cannot know in the way god does, I have only hope and faith, not certain knowledge. I will NOT KNOW UNTIL MY DEATH."
So PRETTY MUCH EVERYBODY is an agnostic, and this "agnosticism" does not inform any of our positions or lend information to the theist proposition of a creator, soul, and afterlife.