[JoeProBono]

Most will admit that ‘church key’ is an odd name for something regularly used to get at a swig of beer. The earliest evidence of the phrase used in print is 1951, but stories about it date from 1935, which coincides with the time that beer was first sold in cans rather than just bottles. Pull tabs on cans didn’t appear until 1962, so the early beer cans required a tool of some kind to open. Nothing complicated—a flat but stout strip of metal with a sharp point which could be pressed into the top of the beer can to punch a triangular hole. This simple, easily made tool was immediately called a church key, taking the name of its predecessor, a bottle opener made of metal, with a round, oval or triangular open shape at one end to grip and pop off a bottle cap.

[TruthWillWin]

Cool but those are before my time. I recall the ones that opened a can on one end and popped open a bottle cap on the other. A simple but effective and necessary tool to carry in your pocket..

[JediJones]

Maybe church key is an ironic statement. Like saying that drinking is a religious experience.