Frankly, I've found the overall environments in these sorts of cafes/hackerspaces to be frustratingly anti-social. And I am someone who would be considered fairly left-leaning overall. But good lord were my hopes dashed when it came to thinking I would meet other folks that would be fun to talk to, just because not 100% of my views line up with the accepted SV zeitgeist.
Plenty of non-christians raised in a Christianity influenced social background, but not raised by Christians, use phrases like that.
With this in mind, things like your point make a lot of sense.
http://www.pewglobal.org/2014/03/13/worldwide-many-see-belie...
But really, not too recently someone thought it was so important they put it on the money and made school children say it every day. I don't think it occurs to most people just how pervasive declarations of religiosity are in America.
I'd imagine this only applies where atheists are in the minority
(Sources: the bible belt, the bay area, and /r/atheism.)