The Tier 4 Religious Tenets, despite being the hardest to achieve, and taking the longest, are some of the most meager.

Why invest the time and effort, if their effect on the game is trivial?

They need to be buffed enough to create an impact worthy of the effort.

And, being the highest tier, that impact should be greater than any of the preceding tiers.

Please uptick this thread if you agree with this in principle, even if you might disagree on the specific numbers I've suggested.

Current

Raise Monuments:  +50 Science on Cultural Wonder

Sustain the Faithful: +20 Stability on Territories if Territories Follow Foreign Religion

Donate Generously: +25  Money Per Alliance on Empire

Meditate Often: +2 Combat Strength on Unit

Suggested Changes

Raise Monuments:  +200 Science on Cultural Wonder

Sustain the Faithful:  +40 on Territories that Follow State Religion

Donate Generously:  +25 Money in All Cities Per Alliance on Empire

Meditate Often:  +4 Combat Strength on Unit

Agree on first three, disagree on the last one, Meditate Often is fine as it is, imo.

I'm also not sure I agree on that change for Donate Generously, though honestly, I'd swap them around, make DG work as you suggest it and take away at least one extra holy site from it and make the Sustain the Faithful give extra two Holy Sites instead, without really changing its Stability effect (I'm against boosting Stability... uh, boosts, it runs away too much, we need less ways to overclock Stability, not more).

But yeah, in general T4 tenets aren't exciting, we know that Vitruvian is supposed to have religion screen rework, I wonder if they'd be able to cram in tenets rebalance as well.

Donate Generously has an additional effect of +2 holy site limit, so it can synergize with some civics and wonders, but the synergy is pretty weak.

Meditate Often is quite impactful already and worth the effort. I agree that the other two choices are laughable.

To me, the main problem is that the effort you put into getting religious tenets... is not really there. It just happens naturally as your population grows. In case that your religion is weak and gets pushed out by another, you can just change your state religion to that one and take it over with your superior population. If your population sucks too, you still get new tenets, although chosen by someone else.

You will get all 4 religious tenets no matter what you do, so I think it's ok that they are not that great. The entire religion system needs to be more meaningful.

I dig up this topic, because I would like to discuss about the current Sustain the Faithful and the change we can have.

I never find any use for it, because if got here, that mean we are pretty much at the top of religion at this moment.

Agreed, the Tier 4 Civics are quite weak, and "Meditate Often" is usually the only one worthwhile (though dzony8 is totally right to point out Donate Generously gives you two additional Holy Sites, which is interesting and also so strange that I keep wondering if it's a bug).

"Sustain the Faithful" is truly weird because by the time you read Tier 4 of a religion, you should have that part of the game in the bag.  I have to believe that tenet is there as a final act against Atheism, and that if Atheism starts to get a foothold in your territory, then at least you get stability out of it.

As for your proposals:

• RM: +200 Science on a Cultural Wonder seems good for a T4 tenet
• StF: +40 Stability on territories that follow state religion seems very strong; a territory is -20 stability to a city, so "Sustain" makes it a wash if you're losing the faith game.  I'd be really hesitant to increase the value and attach it to a situation you're likely to be in when snowballing faith.  I like DLNH's idea of moving at least one holy site from DG to StF.
• DG: I like your changes.
• MO: The existing tenet is fine as is.  +2 is a decent and competitive bonus and is already a strong tenet at this level. 

Nice thoughts overall, and thanks for starting this thread.  I'd love to brainstorm a larger reworking on a lot of tenets, but these T4 ones do need some love.

• RM: +100 Science on a Cultural Wonder
• StF: +20~40 Stability in cities that follow the state religion, this would not break stability in large cities, and would facilitate management and even expansions of the cities.
• DG: I like your changes.
• MO: The existing tenet is fine as is.  +2 is a decent and competitive bonus and is already a strong tenet at this level. 

I see there are negotiations about Raise Monuments value going on, maybe it could scale with era? Or scale with eras since Wonder was built.