Hi all,
I never made it to actually play test the version of faith as I wrote in my previous post as I changed it up before doing so.  I did run with the version I'm posting here though.  Along with this I also have implemented a specialized form of faith use for each character class in order to make it a much more  integral part of game mechanics.  I also inserted "Vices" as was suggested in the other posts.

Here's how it works, and yes its real long.

FAITH
As faith represents one’s commitment to God it is tracked as a whole with a starting value based upon ones piety.  The maximum faith level attainable is ten.  Those of a righteous piety begin with an untapped faith level of three.  Those of an indifferent piety begin with a tapped faith level of one, and those of a corrupt piety do not have faith, instead they have iniquity which is described latter in this chapter.
Faith can be used in a number of ways by all and in a specific way dependant upon the character class of the individual.  Using faith in anyway is not dependent upon the initiative order, one may simply state that they are using their faith at anytime in order to activate its effects.

Untapped Faith
When faith is untapped it confers a positive bonus equal to its level to all D100 rolls, and defense ratings.  As faith is tapped this bonus immediately decreases.  This benefit is conferred equally to anyone that has faith levels.

Tapping Faith
Faith can be tapped (used) in order to assist one in any situation that grants a dice roll of any kind.  Instead of actually rolling the dice one simply declares they are tapping their faith in order to perform the action.  No dice are rolled as the action is considered to have been successful at one difficulty level, or by a roll of twenty five, greater than the required roll.  This bonus applies to any and all rolls that can be made.
In the case of initiative rolls those who use their faith are at the top of the initiative order regardless of any other circumstances.  If more than one person taps their faith for this purpose the one with the highest faith level has their actions first, if any ties occur their actions are considered to take place simultaneously.
With action rolls that force an additional opposed roll, such as a knockdown attack and many condition causing spells and abilities, the auto success is only afforded to one of the rolls as chosen.  If one desires for both rolls to be affected then faith will have to be tapped a second time.
In the event faith should be tapped by both sides of an opposing roll the one who possesses the highest faith level wins for total success, and the loser’s faith is not considered tapped.  If the faith levels are equal then neither is allowed to tap their faith and the rolls proceed as normal.
Though faith may be tapped multiple times in a single turn, as doing so requires no time, it may only be used once per individual roll.
Each character class has a unique benefit for tapping their faith in addition to the uses detailed above. 

Replenishing Tapped Faith
Once faith is tapped it is gone, but only in the since that it cannot be used again until it is replenished.  Replenishing faith requires one to engage in righteous acts that benefit others without tapping faith with the sinful nature.  Doing so will refill one’s faith dependant upon the difficulty and risks involved.  If little risk is at stake in the performance of these deeds then only one level of faith is restored, moderate risk will restore half of the used faith levels (or a minimum of two faith levels whichever is greater), and great risk will restore all tapped faith levels.

Using the Sinful Nature
Man is born with a sinful nature.  This sinful nature can be used to tap faith much like normal though instead of drawing upon their faith in God for assistance in an action one channels their energies from the depths of their wicked self.  Even those who are devoted to God and posses a high faith level have the ability to tap their sinful nature as this is the state of mortal man.  Using the sinful nature to tap faith is accomplished much the same way as tapping faith normally, as it actually does tap faith just in a different way.
The decision to tap faith with the sinful nature is made after the dice are rolled.  This can be very tempting as one will be well aware of the result of what tapping into their sinful nature will bring about.  Using the sinful nature to tap untapped faith grants a bonus of fifty to any roll made by the individual or to reduce the roll of another that is within sight by a like amount.  The sinful nature may also be used to tap tapped faith but the bonus granted for this is only twenty five, not fifty.  Using the sinful nature to reduce the roll of another will not alter an automatic success by one who has used their faith to do so, as the sinful nature cannot override real faith and no actual roll is made when using faith for this purpose.
Faith cannot be tapped normally and through the sinful nature in order to apply a single combined effect to an individual’s action.  However, they can be tapped in the same turn on the same individual for different actions (rolls).
There is one side effect to using the sinful nature to tap faith.  It removes the faith level permanently from the one doing so.  Of course it can rise again to its former level but only through actually gaining a faith level, not through the normal means of replenishing faith.
Using the sinful nature to adjust attack rolls from the critical or mortal wound level to the fatal wound level, regardless of the circumstances, is considered a truly vile act as it involves the sinful tapping of faith out of bloodlust.  Doing so will cause the loss of two faith levels instead of one, as well as cause the willpower role verses gaining a vice toward the action to automatically fail.

Increasing Faith Levels
Faith levels can be increased.  Doing so is much more difficult than replenishing used faith however.  In order to gain a faith level one must go through an entire quest without tapping into their sinful nature.  Additionally, this mission must be one that benefits the Church.  Most any quest a ranking official of the Church sends someone on would be considered as such.

Untapped Faith of One and Zero
When one who is righteous is reduced to an untapped faith level of one they are teetering on the edge of indifference, and if the sinful nature is tapped again they will become of an indifferent piety.  Gaining back faith at this point will require great atonement and reconciliation to God as it is no simple matter to shun God one moment and then beg for His forgiveness the next, especially when one was already sanctified to Him. 
If one who was never righteous is moving from an indifferent piety to a righteous piety gaining a level of faith would be handled normally.
Falling below a zero faith level can happen if one taps into their sinful nature while having a zero faith level.  This will grant a bonus, or penalty, as would normally happen when tapping a tapped faith level but it will also cause the individual to gain a level of iniquity and change them to a corrupt piety.

Corrupt Piety & Iniquity
When one is of a corrupt piety they have something similar to faith though in reverse. This is tracked as iniquity and has a beginning value of one and a maximum value of ten.  If one should fall in their faith level below zero they will gain a point of iniquity as well.
Untapped iniquity confers no constant bonus as untapped faith does.
Iniquity is used by tapping it for the purpose of reducing the rolls of others by twenty five or to increase one’s own roll by a like amount.  Iniquity may also be used to grant all of the user’s attacks the unholy descriptor for a number of turns equal to their iniquity level times two.  Certain entities, namely demons, are capable of using iniquity for other unique effects as described in their creature descriptions.
Replenishing tapped iniquity and gaining iniquity levels is accomplished at the same rate as replenishing faith and gaining faith levels though for being greedy and self serving or by furthering the goals of Nihil.
Attempting to move from a corrupt piety into one of indifference, or even righteousness is possible.  However it is something that very rarely occurs and therefore is of no simple task.  Once a player’s character has fallen into iniquity they are considered lost to Nihil and therefore removed from play as allowing for the player to continue on a degenerate path is contrary to the focus of the Heroes of Leyreth’s game world theme of righteous heroes battling against the dominion of evil.

VICES
Vices are acquired as a result of tapping the faith attribute through the sinful nature.  They are specific to the action that led to their cause and can be very difficult to overcome

Gaining Vices
Every time someone taps faith with their sinful nature a willpower roll of exceptional difficulty must be made in order to resist gaining a vice toward the specific act.  If the roll succeeds all is fine, but should the roll fail the result of the act was so intoxicating to the individual that the next time the same situation which caused them to use their sinful nature arises they must succeed another willpower roll of exceptional difficulty level to not repeat doing so again.  This willpower roll may not be circumvented nor augmented through the tapping of faith in anyway, nor does it receive a bonus from the untapped faith level of the individual. 
For every time the same act is repeated and the sinful nature used to tap faith, whether due to the failure of the willpower roll not to, or the simple desire to do so, the difficulty of the willpower roll to resist acquiring, or succumbing to, the vise cumulatively increases by one.  Once one has succumbed to the same vice three times due to failing their willpower roll it becomes automatic and can no longer be resisted.
There is no limit to the amount of vices one may have and even one vice can lead to the rapid decline of faith in an individual, especially if it is in an act that is fairly common.

My biggest problem now is coming up with a way to remove a vice without resorting to some sort of "Self-Help Group" mechanic or "Vice Anonymous" meetings.  Also do I need to clarify the aspects of replenishing faith and gaining new faith levels or does what I have seem sufficient.

Thanx for the help
Adam

Bing!  Why not require asking God for forgiveness and for help in overcoming their vice.  Perhaps a quest where they have do the opposite of their vice and make amends would work as a mechanic?  I think your statements on replenishment and gaining seem ok but I would give examples of what minor, moderate and severe risk would be?  A list and description of church missions would also help but again, the basic idea sounds alright to me.

Some (minor) suggestions and questions:

Increasing Faith Levels:  I have seen this done in other games but I like the idea of the quest becoming more and more difficult as the rank increase.  Going from a two to a three should be relatively easier than going 9 to 10 for instance.

Untapped Faith:  Cool.  Perhaps inquity could cause negative bonuses to everyone around them and add to attack rolls.  I wouldn't use this all the time but maybe the idea could work for an exceptionally vile villian or possessed person.

Will you have a mechanic for the conversion process? Miracles?

Sean

Talk about not seeing the forest through the trees.  I thought of a hundred ways to remove a vice but actual prayer and quest seemed to elude me, go figure.  Anyways heres what i came up with as well as the amendments for gaining faith levels.

Removing Vices
Vices are difficult to overcome as often times giving into the vice is pleasurable to the individual who has it.  The only way to rid one’s self of these desires is to make atonement for the sin as directed by a priest.

ATONEMENT
When someone falls from a righteous piety or gains a vice that they want to overcome they must make atonement for the act that plunged them into the state they are in.
Atonement is accomplished by confessing the sin in prayer with a priest who afterwards will send them on a quest for the Church that will deal with their sinful act as directed to them by God.  Quests of atonement are usually done alone though in some instances others may be allowed to assist.  After one completes this quest of atonement the priest will again join them in prayer through which they will be forgiven and have their righteous piety restored to them, or their vice removed, whichever applies. 
If someone repeatedly fails in their faith for the same act the sincerity of their confession will come into question and God may deny the atoning quest to them thus leaving them in their sinful state until they are truly remorseful. 

Replenishing Tapped Faith
Once faith is tapped it is gone, but only in the since that it cannot be used again until it is replenished.  Replenishing faith requires one to engage in righteous acts, which should usually benefit others, without tapping faith with the sinful nature.  Doing so will refill one’s faith dependant upon the difficulty and risks involved.  If little risk is at stake in the performance of these deeds then only one level of faith is restored, moderate risk will restore half of the used faith levels (or a minimum of two faith levels whichever is greater), and great risk will restore all tapped faith levels.  Examples of these tasks and their appropriate difficulties are defined below.

Minor Risk – One Faith Restored
1. Escorting non-combatants through semi-dangerous territories.
2. Information gathering quests for the Church.
3. Helping an unfortunate with their situation (non-violent).
4. Defending an innocent (non-violent).

Moderate Difficulty – Half Faith (or 2) Restored
1. Escorting others through hostile lands.
2. Giving aid to others that requires extensive travel or expenditure of personal resources.
3. Defending an innocent from a moderate to difficult encounter (for the character not the innocent).

Great Difficulty – Full Faith Restored
1. Defending a town verse a boss level encounter.
2. Giving up great personal gain (not necessarily money) for the benefit of others.
3. Redeeming the lost.

Increasing Faith Levels
Faith levels can be increased.  Doing so is much more difficult than replenishing used faith however.  In order to gain a faith level one must go through an entire quest without tapping into their sinful nature.  Additionally, this mission must be one that increases the influence of the Church.
Simple quests given by church leaders do not suffice for the increasing of faith levels.  Quests of this nature should be at least marginally monumental in the grand storyline escalating in both depth and difficulty as the faith levels increase to the point that gaining a faith level of ten becomes an epic undertaking

Again thanx for pointing out the obvious

Untapped Faith:  Cool.  Perhaps iniquity could cause negative bonuses to everyone around them and add to attack rolls.  I wouldn't use this all the time but maybe the idea could work for an exceptionally vile villain or possessed person.