[@Guardian Angel Haruki]

Hmm it is hard to say if it is religion or not. The temples we have seen so far are one for combat, one that told the history of Gem war which could have been for training or a never ending punishment, we have seen the gem temple which is more of a home base, the one that the heaven beetle was at but that hardly had any information or anything really religious and the sea spire was said to be a hub. A communication and a place to meet with others if I remember right. The other one was a place to protect the time thing. 

Most of them again had a purpose so not really sure they do have a religion but it could be possible