Mistress Rwebhu Kidh wrote:
The part about faith in God seems to make it a bit unlikely a murderer would be able to use the power, even if he had the ability, but I don't think that would necessarily stand in the way – someone can be capable of having great faith in God's power without being in any way Godly.
That is an interested thought, I have not thought of that possibility. For the most part I was thinking that only followers of GOD have access to this power and that only those who have faith in HIM and the understanding that they can use that power can actually use it.
In this world, the only ones who are granted access to divine power from GOD are angels and followers of GOD.
Angels also include the fallen ones which are better know as demons. To explain how angels have this power I will give the example of a swimming pool with a water hose. The water hose is the permanent link to GOD's divine power and the swimming pool is how much power the angels can hold. If an angle/demon uses all that power at once then it will take a while for their reserve to fill up again just like it would take the water hose to fill up a pool.
Now angels/demons have the ability to lend their divine power to other beings. Angels hardly do this because they are very rare in the world because for the most part they are with GOD in heaven. There is also something that ends up being call demon shard that is a type of hard crystal that absorbs divine power and stores it. The crystal acts as a well and extension of the original source.
The crystal plays an important role in the world, which I will have to explain in detail later.
Mistress Rwebhu Kidh wrote:
Another question, mostly unrelated to the earlier one: Can the tradition-relying power-users use the power even if they have forgotten entirely where it comes from and where exactly their faith is directed? If not, how far can they go from knowledge of God before their 'faith' becomes useless?
I still don't completely understand the way this works, so forgive me if I have it all wrong?

As a general rule the more tradition, the less divine power, or less strength of that power the user has.
You have actually hit on how tradition becomes more complicated. Eventually people become so far removed that they can no longer access that power, either because they no longer follow GOD or because their faith in GOD and the divine power that HE lends becomes too twisted. Think of a whisper that is told around a room, when there is absolutely no essence of the original whisper, then all is lost. This same principal works with tradition based divine power. When it becomes completely about tradition and has no aspect of GOD in it, then they, those who follow GOD, lose access. In the same, if the people no longer follow GOD, then they lose access as well, however these people know how to access the power and would be perfect examples of those who then follow demons and gain access through them.
Don't forget that this discussion is only about divine power and that there is still the access of elemental essence that is used in this world, but that will be in another thread when I get time to gather my thoughts and start it.