What strikes me (besides NSA apparently meaning 'Non-Secular Americans') is that a lot of these posters don't have the design flair and inspiration of, say, WWII propaganda posters.
The NSA's existence was still not publicly acknowledged when some of these were commissioned (the versatile initialism then being "No Such Agency"), which may have shrunk the artist pool.
Most of these are pretty basic workplace safety posters, they don't really have the same purpose (or attention lavished on them) as posters aimed at the public during a war.
They would be using opposing themes today. Those posters were made for their time. Surely you don't think the NSA was led by religious people no more than the Donald Trump administration is led by Christians. They'd be screaming islamic chants in arabic if it helped their political goals.
