A whole lot of you haven't read the Arcanum manual, and it shows. There you go, treat yourself.
https://www.docdroid.net/QEqROKf/manual-pdf
Sure, it's full of holes when if you want to have a sperg-out, but it was never intended to be full-proofed against modern understanding of science;
rather, it's about achieving a stylistic effect - the Victorian era, its struggles and mannerisms (including talking authoritatively out of your own arse about shit of which you only have a vague understanding).
The dichotomy was never about belief in anything, so we can cut this one short. It was between natural and supernatural "forces", which apparently can wax and wane, as well as exert an influence over an area and individuals within
(living near a powerful tech item, in this case a steam engine could reportedly drive individuals mad). It can be slightly counter-intuitive to grasp, because magick is not considered a natural force here,
and the operation of tech items is based on applying natural principles. Magick tweak, suspend or outright break natural laws, which makes complex mechanisms impossible to operate.
Why does the reverse happen? *Shrug* forces and thingamajigs, I reckon. Or perhaps, the more rules you need to break, the harder it gets. I agree it only makes sense if you squint really hard,
but that's what the game bases its main conflict and I'm fine suspending disbelief here.