A better question is, why do you Brits always pluralize things that are singular, like math?
Fine if valid.
Even in a fake question, bringing math into a question directed at theists is a non-sequitur.
It most probably would be flawed.
I'd be far more curious than skeptical, really! Although of course I'd dismiss it, if the whole thing turned out to be just nonsense, and internally inconsistent... But if it had its own sort of consistency, and it could be used for stuff..? I'd probably be extremely fascinated, and want to learn more about it! Although I'd never reject normal maths either, because it obviously works, and we obviously need that! Just... I'd have these simultaneously co-existing tools available to me, one in the form of maths, and the other in the form of alternate maths. ;-)
Which, I think that's a pretty good illustration of what I'm all about, just in general... I'm someone who likes, and finds use for, both spirituality AND science! Although if very specific claims are made, (usually by religion), that contradict current scientific knowledge that has been proven to yield real life results, I will NOT be able to believe in that! So... I'm also the sort of person who, if I ever got cancer, for instance, I'd want both chemo / surgery / radiation therapy AND more alternative treatments! Why not cover all your bases, and do the scientifically proven stuff, but also seek out other avenues that could help in other ways, for other reasons?
..That's basically where I'm at. :)