If you don't capitalize "catholic" then it just means "universal"

That's true. Not writing "Catholic" was an error. It's not like the Catholic religion is any more universal than, say, the 'Liberal' party here is particularly liberal. Names get capitals so we don't confuse them with real words.

and not capitalizing "God" is like making a point of writing Eliezer's name as "eliezer" just because you think he's the Antichrist.

But here you are wrong.

When referring to supernatural entities that fall into the class 'divine' the label that applies is 'god'. For example, Zeus is a god, Allah is a god and God is a god. If you happened to base your theology around Belar I would have written "the Alorn god". Writing "the Alorn God" would be a corruption of grammar. If I was making a direct reference to God I would capitalize His name. I wasn't. I was referring to a religion which, being monotheistic can be dereferenced to specify a particular fictional entity.

Other phrases I may utter:

• The Arendish god is Chaldan
• The Protestant god is God.
• Children believe in believing in the Easter Bunny.

Is there some justification I'm missing?

The historic conceit that makes using capitalization appropriate when referring to God does not extend to all usages of the word 'god', even when the ultimate referent is Him. For all the airs we may give Him, God is just a god - with all that entails.