Miracles are too effective.
There. Someone has to get the ball rolling?
I would like to list all reasons that, I think, support my statement:
Miracles in general give characters options IN ADDITION to the normal skill system. (Of course this is valid for crusaders powers and the few other guilds with their unique abilities as well. It is not the same as with miracles though, because if you take for instance the scribes, learning scroll magic takes A LOT longer than learning miracles. And they still don't have access to very useful miracles like the breeze miracle - I'll explain on that in regards to the breeze miracle a bit later.)
What do I mean when I write that the miracles give characters options in addition to the normal skill system?
Simple: take the uner miracle. As far as I know two cleric guilds can use it (Asral, Sathos) and hence can, at will, create glowing missile objects on their own. The non-cleric characters do not have this option available for their characters. Of course they can ask other characters for those objects, but it is not the same, as they depend on other characters, and not on their own character. If you, say, have two characters with missile skill 100, then the character who can use glowing arrows has a huge advantage over the other character. And the non-cleric character CAN NOT compensate for this on his own, simply because he has no access to this feature, as he is not a cleric. (The miracle's effect may drain mana and thus have a slight drawback, but even if a character has no mana left he can still shoot arrows/bolts. And I mostly refer to having an extra option available anyway, not about how effective the miracle in question is.)
There are more examples of course.
farmour is one - it gives characters an advantage in melee as they can trade "damage for damage". The cleric character is hit but returns some damage to the one who is hitting him.
The old (and somewhat buggy) slay miracle gave Sathos a reliable method to deal damage to a target. Not many remember that iceskin was actually added to counter the old slay miracle. That's right, iceskin was added lateron, and it is also a reason why it so powerful - you eat the damage from slay but return a lot of that damage as well.

Nowadays, slay seems less effective, but iceskin is still extremely strong. Which, by the way, is another example of giving a character an option in addition to the skill system: you engage such a character in melee and will reliably eat the damage when you hit him. Which is A LOT of damage and no way to "work around it" ...
One miracle that I think is way too effective is the breeze miracle by the way.
It shortens the recovery time of characters, which affects pretty much everything. It especially affects the skill training of characters today very positively.
But first let me explain why I think the breeze miracle is too effective:
The breeze miracle can in effect be permanently on. Characters can even use triggers to auto-recast it.
When the breeze miracle is on, it makes the playing time of that character more efficient. Why? Because you recover mana, wounds, fatigue, and this means you can continue training more readily.
Given how the skill system works, favouring those who fight strong opponents, this gives them an advantage here - you reduce the downtime before you continue more and more grinding of monsters. (Mind you, I think grinding monsters is extremely boring - I'd really like to see the MUD move away slowly from favouring combat that much. All it does is favouring some characters in PvP and these characters are often only interested in ... more PvP. How boring ...)
That a character learns skills more easily that way is not the fault of the breeze miracle alone. It is simply how the skill system works. Experienced players can "squeeze" out more skill improves that way, too.
On top of that, the breeze miracle helps in PvP. At the very least when you retreat from PvP, you do recover faster, and can re-engage again.
Cure type miracles help as well ('cure', 'frenewal', 'ldrain' - the latter is a modified damage dealing cure miracle):
If you are a cleric, you can use such a miracle, and heal yourself (or others).
If you compare this to a non-cleric character, he has to wait longer. He simply has a longer recovery time. The character can partially compensate for this if i.e. he is or was in the skald guild, singing the soul song. But a cleric character can do the same and use songs, in addition to the miracles. Again, he has more options available.
I also think that the change from how miracles used to work - they could be interrupted more easily - to today's mechanism made miracles more effective. Same with the beseech deity skill. In the past, clerics had to train every miracle and had masteries in them. This was tedious, but at least it was slow, and took the clerics a long time to train. Nowadays, you just have to use a general skill and that's it.
Last but not least, non-cleric guilds used to have skill boni, which made learning certain skills easier/faster. This no longer seems to be the case, instead a cleric nowadays can learn faster than non-clerics due to how effective miracles are.
There are many more miracles that affect the gameplay, such as fast ways to move on the "game map", but I stop here talking about specific miracles.
In a way I am saying that miracles today are too effective and some changes should happen.
Miracles also affect the non-cleric guilds as well: how can a Shaolin character or in general a non-cleric non-special-warrior (especially guildless characters !) compensate at all for this?
Scribe magic takes a long time and preparation, and training is harder too ("harder" as in it "takes much longer"). And perhaps such a character has IC reasons not to *want* to join a guild like the Scribes, or just does not want to learn magic at all for whatever reason. Such a character will be at a permanent disadvantage. Should the game really want to encourage maximizing every PvP strategy? But that's a general question, not one specifically pertaining to miracles.
So let me go back to miracles:
I am not saying: "nerf this miracle, boost that miracle". These are just minor details. Whether a miracle does x damage or x+50 damage isn't that important.
I am not saying: "make life of clerics harder" per se either. There may be other reasons why playing a cleric isn't a lot of fun. (PvP would be one very big reason here, PvP has a too high, negative impact on the gameflow right now.)
I am saying that miracles give certain characters a too big advantage in general in several regards, with no real FEATURE-drawbacks.
Now, no matter if my statements or opinions are shared or not, I would like to offer some ideas that could address some of these problems. Yes, it means that clerics would lose a bit from their effectiveness ...

- Make miracles depend more on mental stats. WIS is a requirement for some miracles. Why not have DIS and INT play a bigger role in how effective a miracle is?
- Make it harder to maintain certain miracles. One that would come to mind is the breeze miracle and iceskin. But in general, just make it harder to maintain too many miracles at the same time. They could drain mana after a certain threshold too.
- Make miracles depend on more skills. For example, the components of the miracles could have to be learned slowly. Gestures, verbal requirements ... and so on and so forth. One or two new skills could be used here. I don't know about the names... "component knowledge" or ... "applied rites" ...
You could even split miracles into two groups, for the skills: one skill for low power miracles, another skill for high power miracles (and this one would be a LOT harder to train too)
Beseech deity could be harder to raise as well in general. It seems as if it can be learned much faster than weapon skills, and given how much it affects all miracles, it should be more difficult to improve. Recall that in the past every miracle was like a "skill". You could have a mastery of 100 in heaven fire but only 60 in fbolt (because fbolt just wasn't as impressive as hfire, hence clerics didn't spend as much time requesting it in the past, thus had a lower mastery in it). Keep in mind that I am not advocating a return to one-mastery-per-miracle. I am just saying that the change towards beseech deity skill kind of made miracles more effective than they used to be.
- Also, beseech deity could and should be changed in one important aspect: it should be specific to the deity in question.
Right now you could train up to a very high beseech deity skill as Asral cleric, quit, and join the Sathos and retain all that knowledge without EVER having requested a miracle from Sathonys. I think this is bad. I would even say, be radical here and cut the beseech deity skill down to half when LEAVING (or being expelled) from a clergy.
This way, if you had a skill of 90, leave the Asral clergy, and eventually join the Sathos, your beseech deity skill would be only 45. Right now, it would be retained at 90 if you join another clergy quickly. I don't think this is fair, and I would like to think that beseeching deity x is different from beseeching deity y anyway.
Again, keep in mind - in the past, when you changed to another clergy, you had to relearn all miracles, or at least start from 0 in these, often new miracles. A mastery of 100 in hfire would not have helped you at all with the smite miracle, where you would have started with 0. But thanks to the beseech deity skill right now, you can retain basically everything here and request smite miracle without any problem whatsoever ...
- Give other characters some way to counter or interrupt miracles more easily or a chance to lower the effects of some miracles. In the past it was rather easy to interrupt miracles.
How about more magical, expensive items that could give specific resistances?
Or critical hits having a chance to interrupt the "channeling" of the deity's power into the cleric? After all, you need a sound mind and body to be able to "channel" that power anyway. (And yes, I know that there are still ways to interrupt miracles, they are just significantly less common than how it used to be...)
PS: Edit. Perhaps this should be in the idea section ... but then again just take this less as an idea, and more an invitation to give your opinion about this topic. I don't really mind if miracles stay the way they are, or whether they are changed - my main point is that they CAN affect the gameplay a lot.