[quote=@ArmorPlated]
Edit, because I always think of something more I want to say or ask: How common is Light magic among the casters of Hyrule?

Edit 2: Anyone know what the primary religion of Hyrule would even be called?
[/quote]

In the games we really only seem to see Zelda use it, as far as I know, outside of individual items or temples that use it as a theme. In fact I want to say a few times (Minish Cap, possibly some others) "Light Magic" or "Light Force" is a unique ability possessed by the Royal Bloodline. But OoT established so many of the series' staples, and in that one it was really more the domain of Time that was the Royal Family's schtick and the Light Sage was just some dude who could turn into an owl. Maybe he was part of the Royal Family or something though.

Magic in general in Zelda actually isn't common, though. Outside of Link, and outside of the particular items that do particular things, how many actual wizards on the level of Gandalf or even Harry Potter do we see? Major villains, like Agahnim and Veran and Vaati, are the only ones who come to my mind.

As for the religion, I guess it would depend on whether this setting includes Goddess Hylia up above the usual Triforce group. If Hylia is included I would think it should be called Hylianism, whereas if it's only the three maybe it'd be called something like Trinitarianism or something. 

I assume most of this would just be up to [@Product]'s personal taste though.