I take Jefferson’s words to heart...when he writes out and explains why he believes what he does which is usually the case.
Unwin did a study based on assumptions so bad that it would make a global warming nut blush.
The problem is that you treat atheism as an ideology, it’s not. Do you believe what you do because you’re a theist? Hell satan worshipers are theists, it doesn’t mean much at all! Does my not believing in a god tell you my politics? My ethics?
The only countries in the world that are officially atheist are the communists ones and that’s because it’s central to that godforsaken philosophy (no pun intended). However they’re tyrannical because they’re commies, not because they’re atheists. The inverse of what’s you’re saying is that to be free a country has to be officially theist, and the US obviously isn’t whereas other officially theist countries aren’t anywhere near as free although some are.