Yes, of course atheism is the negation of one sort of religion, but certainly Hindu 'gods' come under that heading.
And when I use 'thinghood' I am merely trying to coin a term which partially identifies that the focus of what we call 'observation' on 'an object having location'. (Observation and objectivity both being philosophical quagmires)
But your apparent claim that the status
of mathematical models has no implications for philosophy is breathtakingly simplistic, as indeed is your casual use of the word 'existence' (human or otherwise) since you presumably see it as relating only to 'independent existence of things
Also, as a published scientist myself, I am aware that so called 'success' of any paradigm /model is ultimately open to revision, and that a loose consideration of Godel's incompleteness theorem reminds me that axioms are ultimately based on 'faith in continued success' rather than 'logic'. Hence your attempt to separate 'science' from 'religion' tends to be a rhetorical posture, indeed a weak act of faith in itself ( protecting that hard won
degree), rather than a strength.
BTW The Feynman adage which you tend to imply... ' forget philosophy...just shut up and calculate'... is good for countering many critics of scientism, but can hardly be a fallback position on a thread on 'atheism' and 'spirituality'.