OP here. I am an atheist with zero spiritual beliefs in the sense you are talking about. When I say "spiritual" I mean "dopamine-inducing", full stop. There is some cool stuff in math, science and in our crude attempts at morality that can be seen as "deep"/"spiritual" in its poetic purity, but this can be appreciated completely devoid of any belief in any kind of higher power. That is what I'm referring to.