The Agnostic view of gods is that, while there may be no evidence for them, this does not prove their non-existence; absence of evidence is not evidence of absence. You cannot prove a negative therefore you cannot prove non-existence.
Taking this to its logical conclusion, the same case can be made for any possible notional idea. The universe of all possible 'truths' is bounded only by the limitations of human imagination. For example, you may imagine your loft to be full of scientifically undetectable hippos.
The Agnostic purist would argue that the hypothesis that this proposition is not true cannot be proven and so we must allow for the possibility that your loft is indeed full of invisible, weightless, odourless hippopotami. Indeed, it would be dishonest, even bigoted, to argue that the idea is nonsense; that there are absolutely no undetectable hippos, in your loft.
Despite the absurdity of the conclusions to which this this argument can lead, it seems, on the face of it, a logical, irrefutable and intellectually honest position to adopt. Certainly you can't prove a negative, so is the Agnostic right to believe that there may indeed be lofts full of undetectable hippos, and there may be gods, even the Abrahamic god of the Jews, Moslems and Christians, and their various offspring sects? Is it right to take the view that those who DO believe those things MAY be right and that their beliefs can't be challenged with science?
But hold on a minute; are we really seeking here to do the impossible and prove a negative? Isn't there an assumption underlying the Agnostic argument that any notional idea MAY have a physical reality? Aren't Agnostics assuming something positive which they must prove, and which IS falsifiable in a scientific manner?
Are they not assuming that there is some mechanism by which anything which can be imagined by the human brain can leave that virtual world of human imagination and gain physical reality?
If so, their claim becomes a positive, testable hypothesis which can be falsified by science.
If not, then what exactly is the basis of the assumption that any proposition which can be dreamt up MAY have a physical reality, the possibility of which should be acknowledged?
So, a challenge for Agnostics: establish by science that this transfer mechanism exists and the human mind can create physical reality by thought alone, and you have proven the underlying assumption behind agnosticism. The test will require you to demonstrate repeatable instances of a physical reality brought into existence by thought alone, which did not pre-exist your imagining it.
I await the result with interest.