Religion in Lorgaire is based around social organizations and pantheons rather than a specific deity in most cases. A paladin might thus follow a noble warrior god first and foremost, but still be of the same faith as a wizard following the god of mystery and knowledge. Another paladin dedicated to a different religion might have very different views on theological issues, although still devoted to the cause of law and good. Deities in Lorgaire are not specific to a race, although religious organizations and practices may not be shared or recognized as paying homage to the same entity.
The Nature of the Gods
In many RPG settings deities are manifested beings that characters can interact with directly. No one considered sane questions the existence of the gods. An experienced planar traveler can drop by Asgard and get into a wrestling match with Thor. Fundamentally, deities are just very powerful creatures in the prototypical setting.
In Lorgaire the interaction is less clear. While many deities are portrayed with anthropomorphic iconography, they do not walk the material realm or even the near planes. If they exist at all, deities inhabit a distant realm of existence — a reality that cannot be reached with mere spells or powers for interplanar travel. Some religious philosophers believe that the souls of exceptional adherents travel to the realm of the gods and join them eternally, instead of re-entering the cycle of souls; while this is a comforting belief, it has never been proven, and the rare devotee transported to an immortal realm before the moment of death can be drawn back into the cycle should they perish on return to Lorgaire.
This raises the question that if the gods may not even exist, what do spells such as Augury put you in contact with? Why do extraplanar allies answer your call or summons? Divine magic exists, and most people believe these gifts are bequeathed from gods. Some entity is providing answers to prayers, and priests believes it to be their deity. A skeptic may propose it to be the collective unconcious or merely a philosophically aligned powerful outsider; and as for aid from planar allies, reverence for the philosophical concepts of the gods is not limited to mortals. Outsiders including celestials and fiends also worship deities. An archon dedicated to law and order may never have seen the face of the goddess but it believes in her principles implicitly, and it will aid those mortals who fight in her name.
Ultimately, belief in a deity is a matter of faith. Each deity represents an ideal and espouses a certain code and approach to life. When you embrace the path of a god, you become part of a community in the mortal world. Perhaps, if you are deeply spiritual, you will gain the power to perform miracles of divine magic. This is what people expect of the gods of Lorgaire: they affect the world by guiding and empowering their followers, not by manifesting and taking direct action.
Actions Versus Belief
A spellcasters alignment does not have to perfectly match that of his deity. A lawful evil cleric can worship a chaotic good god, and he may still receive spells and granted powers. The main question is what this divergent alignment means. It may be that the priest is betraying the ideals of his church. It is equally possible that the priest fervently believes in the principles of his religion but approaches them in an unusual manner.
For example, an inquisitor may be lawful evil, and is willing to torture and kill in the interest of what he views as "the greater good," and he truly believes that he is carrying out the wishes of the crusade when he does so. Good-aligned members of the church may find his methods abhorrent, but the question is whether his results serve the goals of the church. In the minds of the people, questions of good and evil are far broader than "what can be detected by detect evil?" When the crusade against lycanthropy began, the soldiers knew that there were individual lycanthropes that were not evil. But lycanthropy itself — a curse that could corrupt the body and soul of anyone it touched — was seen as evil, and the sacrifice of innocents was necessary to purge the greater darkness.
Polytheistic Clerics and the Cleric with No God
The preeminent religions of Lorgaire include the worship of multiple closely associated deities. Most people worship the entire host and address their prayers to whichever deity suits the needs of the moment. A traveler may offer a prayer to whichever lords over the sea or storms when boarding a ship, give thanks to the patron of hospitality or indulgence after an excellent meal, and make a sacrifice to a god of protection or theives when a pirate ship appears on the horizon. A priest tending a shrine may serve a particular sovereign, but a cleric can choose to worship the pantheon as a whole.
Faith and devotion is not exclusively the purview of abstract philisohical principles though. Servants dedicated to an elemental or demon lord, or a fanatic dedicated to a great hero from legend, can receive the boons of religious faithful. However, it may be that belief filtered through the concept of awe inspiring physical entities limits the scope and strength of aid which can be granted.
It is also possible for a cleric to have no god and still perform divine magic. This is not, however, the same as having no beliefs; it still requires a strong commitment to an ideal or a philosophy. The cleric needs to devise his own system of belief and explain how it justifies the domains he has selected, and the GM always has the authority to disallow a combination of domains. The goal is to allow a broad range of personal faiths and social customs — not to encourage players to pick domains based solely on granted abilities.
Divine Magic in the World
Arcane magic is a science or art. It is a force that can be controlled through formula and incantation. Divine magic is quite different: it is a miracle of faith. Clerics are the crusaders of the church, skilled in battle and capable of channeling the power of their deity. The vast majority of priests are experts who possess little spellcasting ability. An average religious expert might possess a variety of knowledge or Lore specialties, Medicine, Diplomacy, and Society, and use these skills to provide spiritual guidance to her community. A cleric of any level is a remarkable figure.
A side effect of this is that most temples do not sell divine spells rites of their god for mere gold. If the petitioner is a loyal member of the faith, an adept may aid him at no cost, or the adept may set a price based on the abilities of the adventurer, calling upon him to make a sacrifice to prove his faith or perform a service in the name of the church. The more powerful the spell, the more significant the sacrifice or service. If a nonbeliever serves the cause of the church, it's possible a priest will provide assistance, but a temple is not a marketplace. No one can demand a miracle as if purchasing a spell from a wizard's guild. Needless to say, this makes a character's choice of religion an important decision. A cleric of a moon worshipping lycanthopic cult will never consider helping a follower of the crusaders dedicated to eradicating them, and you'd be soiling your faith even to ask.
There is a notable exception to this rule: corrupt clerics, or those disillusioned by the mysterious relationship between the gods and their adherents. There are priests who are more interested in lining their pockets than serving the faithful. If you can find such a cleric, you can purchase any spell he can cast, at standard prices.