Unfalsifiable, nonscientific statements can be trivially consistent with a scientific theory only because the former statements are vacuous and are unworthy of refutation. That's not enough for you to hang your hat on.
I didn't say the background knowledge of modernity entails atheism, as in you could deduce the latter from the former. I say that that background knowledge tilts the burden of proof in atheism's favour, for just the reason you've already conceded when you say that theists have an easier time talking about God with other theists. Birds of a feather flock together. Modern societies are effectively secular, which is the essence of Nietzsche's warning that God is dead. Theism is no longer the default in these societies. That's what it means to say the burden of proof is no longer so much on the atheist, whereas it certainly used to be when the opposite was true, before the modern social and cognitive revolutions. This isn't as complicated as you're making it out to be.
You attempt to reduce the burden of proof issue to the fallacy of an appeal to popularity. It doesn't matter how many atheists or theists there are in the world, especially since most people are hypocrites. Someone can call herself a theist even though she lives effectively as if there were no God. No, what's relevant to the burden of proof is the zeitgeist, the cultural background, the major events that define recent history which shape our way of life regardless of our hypocritical postures and superficial conceits or self-images. Christendom used to be central to that background, whereas now it's modernity (as set out by Dostoevsky, Nietzsche, Kafka, Freud, Darwin, Adam Smith, Marx, the Scientific Revolution, the Enlightenment, the French Revolution, the world wars, and so on and so forth).
Naturalists have all kinds of reasons for dismissing theism regardless of the latter's trivial consistency with scientific theories. The theistic narrative isn't scientific. The very triviality of that consistency is a warning sign, just as the epicycles that were added to Ptolemaic cosmology to make it consistent with the data rendered that account less probable and eventually unscientific. Theistic statements are poetic, political, and therapeutic, not scientific. Those statements can therefore be dismissed on all kinds of methodological grounds beyond just parsimony.
But yeah, adding magic and personhood to elementary forces runs afoul of Occam's razor, assuming naturalistic explanations work better. And the more concrete and falsifiable theism turns out to be (as in the exoteric renditions), the less consistent it will be with naturalistic models. (It's interesting, though, that theoretical physics may be running into difficulties, which could cast doubt on methodological naturalism.)
I address the question of whether atheism is just the lack of a belief, in the article linked below.
