Religion-Themed Set

RW02 is pretty nuts.  I like what you're trying to do but I'm not sure if white is supposed to get such good card draw.  The limiting of the max hand size is a step in the right direction, at least.

RW01 looks similar to Archangel of Thune.  Was that intentional?

CU01 could be a tad strong?  I don't know if blue usually gets flying bears at two mana.

CU02 could also become obnoxious in the right deck.  I'd increase the cost on the ability to just to be on the safe side.

CU06 feels weak.  For two mana, you're really only going to be milling five cards, and on top of that you can only do it in response to an opponent's spell.  If you want this card to be playable in any format outside limited, it needs some help.  Maybe have it mill seven?

And on that note, CU09 is a bit too strong for 1 mana.  I'd have it mill only 5 or 6, especially if you're going to push a graveyard mechanic for the set.  Targeting yourself with this makes it way too easy to stock up your graveyard.

CU10 could be called "Burden of Knowledge" or "Horrendous Burden", maybe?

CB02 seems a bit strong for 2 mana.  Maybe take off the flying?  Or drop the power by 1?

CB07 is too good.  Unconditional kill for 2 black mana is so good that milling yourself for 1 is not even a noticeable drawback.  In some decks it's even an upside.  This needs either a condition or a mana cost increase.

CB08 could target nonland/noncreature cards to fit with the flavor of gnostic, maybe?

UB01 has a similar problem to CB07.  The drawback of milling yourself for two isn't enough to balance out the cost reduction on the card itself.

I noticed a theme on some cards where the cost was reduced in exchange for the milling.  It's not quite a full drawback and cost shouldn't be affected when making cards with it.  Also, the Ritual mechanic is a "drawback" mechanic, which is considered a no-no nowadays because they are perceived as unfun.  I think you could solve both of these issues by incorporating a cost reduction into the mechanic, then increasing the mana cost.  Maybe something like this?

UB01 - Prayer of Malice
Sorcery -
Ritual 2 (As an additional cost to cast this spell, put the top two cards of your library into your graveyard. Then, if there are seven or more cards in your graveyard, CARDNAME costs less to cast.)
All creatures get -2/-2 until end of turn.

CR01 is a prime candidate for this cost-reduction version.  Increase the cost by 1 (so that it matches the normal Act of Treason mana cost), then add the cost reduction on the mechanic.

RL01 is scary.  I think it might be balanced, though?  It's hard to say.  Lands that tap for so much mana are always a toss-up.  Creatures that can recur for free (such as Phoenix) can maybe break this card?  Again, hard to tell just from looking at it.

Maybe your Fervent-Faction mechanic could be something that cares about combat damage?  Something like this?

Teamwork (You choose how combat damage is assigned to creatures you control with Teamwork.)

That reinforces the community aspect and also allows them to be really strong in combat.