Ok, I've decided on what the temple and each of the altars does:
Core Temple: Neither sunlight nor holy items/beings can go into the temple nor can they be generated within it
Mina's Altar: By praying at the altar, one can gain a power based on one of Mina's domains or be destroyed from trying to get more power than one should have. The effect only occurs if the being wants to try to gain a new power.
Lily's and Kyouko's Altar: Increases the strength, speed, and intelligence of any twins blessed at it by a religious leader.
Gravas' Altar: Can reach into the chalice on the altar: If worthy, one will get a weapon of a quality better than what mortal hands can create, while if unworthy, one will be blasted backward violently by water and wind. Please do note that the obtained weapon will not initially be an Artifact or Divine Artifact, just a weapon of good quality.
Magnas' Altar: Upon touching the altar directly, one can access its stored power if worthy or be electrocuted if unworthy.
Kyuu's Altar: Can pray at the altar to get a staff made of the finest and sturdiest woods, however if unworthy, all blood will be drained from one's body.
Suna's Altar: A protective barrier forms around anyone who prays at the altar.
Each altar will be lovingly crafted so I'm wondering whether I could get them as reduced-cost Artifacts.