Disapproval
It is not easy being faithful to a divine power. Both Gods and Elemental Lords expect and demand obedience from their clergy. When a cleric selects a faith to worship they also select two domains from the lists of domains attributed to their faith.
Each domain includes a code of conduct statement which provides the cleric with one active behaviour they must act upon each day to avoid the disapproval of their divine power. Each day when clerics renew and prepare their sleeps, their divine patron judges them on their actions the previous day. For each each code of conduct violated the cleric gains 1 point of disapproval (so if they ignore both codes in a given day they will earn 2 points of disapproval). When a cleric has received 20 points of disapproval they are considered to be an ex-cleric.
Purple Duck Note: At my table we used glass tokens to represent disapproval. This was an easy way for both the player and GM to actively track the amount of disapproval without it becoming a burden for either side.
You Have Gone Too Far
It is also possible for a cleric to earn disapproval throughout the day if they act specifically against the ethos of their faith. For instance, the Goddess Gerana, is the patron saint of good and just rulership. You is an active supporter of the Middle Kingdom and its rule of law. If a cleric of Gerana were to strike against the nobility and the church by fomenting rebellion they can earn disapproval points by GM fiat. This source of addition of disapproval should be limited to a maximum of 4 points per day and should never be enough for a cleric to become an ex-cleric. It should serve as a warning or heads-up for the player who is running the cleric that they have wandered dangerously toward heresy.
Ex-Clerics
A cleric earns 20 points of disapproval you loses all spells and class features, except for armor and shield proficiencies and proficiency with simple weapons. You cannot thereafter gain levels as a cleric of that divine power until you atones for you deeds (see the atonement spell description) or reduces you disapproval to 0 points.
Reducing Disapproval
One of the worst things that can happen to a player character is to lose access to their class abilities. There should be several ways in which the character can redeem themselves in the eyes of their faith along the way to reduce the amount of accumulated disapproval. Below is a list of suggested ways that you could remove disapproval points.
Atonement: The atonement ritual removes disapproval from the cleric but has a significant cost associated with it. In addition to the cost of highering someone to cast the spell, the magical ritual transforms the material wealth of the cleric into divine forgiveness. The wealth is usually collected by an powerful outsider aligned to the faith. (500 gp = -1 disapproval)
Charitable Acts: All faiths recognize service to the community as good for the faith itself. Even Nemyth Vaar, the god of betrayal, serves the community though the staffing and support of asylums on Porphyra. Each day that a cleric is involved in charitable acts that support their church they lose 2 points of disapproval. (1 day of charity = -2 disapproval)
Conversion: There is no greater devotion that can be shown to a divine power than drawing others to their worship. This conversion must be authentic and without the use of guile or magical manipulation. (1 converted follower = -1 disapproval)
Study: The work of the faithful is never done. If you have access to a temple of the faith there is always work to be done such as providing service, copying scripture, fasting or praying in isolation. (1 day of study = -2 disapproval)
Suffering: Some faiths emphasize the importance of physical suffering in the service to their faith. For such faiths, a cleric may suffer some kind of physical torment that deals ability damage such as torture or flagellation. (1 point of ability damage [physical] = -1 disapproval).
Tithe: If the cleric, on a monthly basis, remembers to tithe to the church a portion of their wealth they can remove an equivalent amount of disapproval. (10% wealth = -1 disapproval)