So I checked out the Holy Mage (finally) that you wrote up.
It looks good to me, everything seems really balanced for a casting heavy class, which is hard to do sometimes.
Only thing you did not cover was weapon proficiencies. You mentioned the mage gets bonuses with the deity's favored weapon, so you may want to give proficiency with all simple weapons plus the favored weapon and no armor proficiency. Or reduce the amount of spells per day a little and give them the ability to cast arcane spells in light armor. The amount you reduce will all depend on how powerful you want them to be.
One thing I really liked was the limiting of divine spells up to only fourth level, very smart, but the drawback of that is that higher level healing becomes difficult as people do eventually need spells like heal
in order to recover after a major battle.
All in all, though, you did a good job on your first class and have a good understanding of mechanical balance. Great job, dude.