Stating a contrapositive for theism-nontheism is a difficult thing to do, but I wouldn't say it's logically impossible.
maybe including another variable in concern of the two would help to advance your argument.
You would need either a soulutional evidence, such as death, or a logical inconstence, such as the inability to know.
I believe you tried the later previously but could not successfully drive in it's purpose.
So stating something along the lines of,
"From having such a lack knowledge there is a fallacy in even the idea of a God or set of Gods either 'being' or 'not being', the simplicity lies within seeing the belief defined, redefined, and watching those who either 'agree' or 'oppose'. There is no validity in either statement therefore they both are either 'true' or 'false' until proven otherwise, so there is simply no point in the display of either side nor bothering to pick a side."
would be accurate of an argument from your perspective.
I am not well antiquated with the formatting of such arguments, so please forgive the roughness.
I also prefer the argument of an "opposite yet same" position wherein death is the end variable.
A, "why bother when we have a 100% way of finding out the day our brain terminates all functions".
But that doesn't seem to fit the point you are trying to throw across.
I could also have completely missed the point and stated all of that while only understanding half of a whole belief.
In that case disregard this post in its entirety.