Did a quick search and didn't see discussion of this on the various "how-many-different-ways-can-I-found-a-religion" threads. Playing an Immortal game with Babylon, so I ignored shrines, etc. and made no effort to build faith (got 4 faith from a visit to La Venta). As I was building the university in my capital, the Celts enhanced, so I thought, well, that's that. But, I still wanted to build faith to buy a late-game GE with Order and/or late-game GSs, so I started throwing up shrines and temples and then I thought -- why not build Hagia Sophia and plant the GP to get SH-level faith accumulation? So, when uni was done, started building Hagia Sophia. Out popped a GP and, to my amazement, it allowed me to found a religion, including picking a belated pantheon belief. And the best part is I got Messenger of the Gods, Ceremonial Burial and Feed the World (another great use for those shrines and temples). I did not know you could do this.