Then it occurred to me... The Freemasons supposedly take their origins from medieval European guilds of stone masons. So what? Well, in German, a Schreiner is a “carpenter” or “cabinet maker”. Seems plausible. If stone masons are at the foundation of Freemasonry, why not carpenters at the foundation of Shriners?
However, this might be one of those cases of inventing connections where they don’t really exist. Wikipedia* here shows nothing to do with carpenters or other medieval guilds. In fact, the Shriners’ mystic shrine seems like it might have been invented out of thin air to satisfy the needs of the moment: creating a fraternal order for fun and fellowship (in 1870...another case against medieval origins).
But I’m not giving up. I haven’t found the German etymology of Schreiner yet, but I do know that a shrine, like in a temple, is Schrein in German. So I checked my OED and found the following for
shrine (n.): O.E. scrin "ark of the covenant, case for relics," from L. scrinium "case or box for keeping papers," of unknown origin.
One online etymology dictionary isn’t the final authority, of course. In this case, that’s a good thing, because I’d suggest that the unknown origin of shrine above might have something to do with building cabinets or wooden cases to hold something special. When I find the etymology of German Schrein, I won’t be surprised if there’s a connection to that same Latin scrinium.
Oh — one more thing. The Ancient Arabic Order of the Nobles of the Mystic Shrine was started among members of the Masons in England. To be a Shriner, you have first to be a Mason. The plot thickens...
* Now’s as good a time as any to highlight that I do not look to Wikipedia as the ultimate authority of what is and what should never be. However, it’s a most excellent first stop to learn about something. I include the Wikipedia links in order to “cite sources” and provide readers a jumping off point to explore further. Same holds for my OED, which is just one among many etymological resources for English words.