Are there any rules for a Cleric to change his faith?

Question

There are rules for a Cleric who loses faith, and how to regain his standing through atonement.

But what if he abandons one faith entirely for another? Presumably his new god/faith should be picking up where the other leaves off, so spells aren’t interrupted, and further he probably should be changing his Domains to ones used by his new faith, but does any official book actually describe this process? Does his new faith require atonement for his prior faith in another religion? Is there some kind of interruption time period, where he doesn’t get spells? Is the actual process of substituting Domains explained?

Because the lack of rules that I’m looking at almost seems to imply that a Cleric cannot change faiths.

I’m really looking for book citations here, because this is specifically for the sake of determining what the rules currently are to better judge how changes might affect them. I have plenty of my own ideas about how this sort of thing should be handled, most of which rely on eliminating as much of alignment’s mechanical impact as possible, but that’s not really relevant here.

If your answer is that there are no such rules, I’d like an idea of how certain you are of this. For example, I could not find any such rules in Player’s Handbook or Complete Divine, the first two places I looked. Knowing where the rules aren’t is useful.

Answer 1

There is no such rule in the setting-independent supplements that I know.

But setting-specific supplements are another story.

Forgotten Realms Campaign Setting, p233 or something:

Changing Deities

It is possible for a cleric, druid, paladin, or spellcasting ranger (or any other divine spellcaster) to abandon his chosen deity and take up the faith of another deity. In doing so, the divine spellcaster loses all class features of the abandoned deity. To progress as a divine spellcaster of another faith, the character must go on a quest for his new church (often the recovery of a lost item of some importance to the deity), then receive an atonement spell from a representative of his new faith. Once these two conditions are met,the character becomes a divine spellcaster of the new deity, and if a cleric,he chooses two domains from the new deity's repertoire. The character then resumes the class features lost from leaving the old faith(so long as they are still applicable — turning or rebuking undead ability might change, for instance)

While not worded ideally, these rules implement a simple idea: the same atonement spell does the job.

Answer 2

There is no way for a 3.5 edition cleric to change their patron deity, by the rules.

There exists no Wizards-legal way for a cleric to change their patron deity. Changing your deity is not mentioned in any books that I have seen (which is most of them). The only thing similar that I know of the the process by which a fallen paladin can become a blackguard and trade in paladin levels for blackguard ones.

For places where I know the rules aren't, I'd say that such rules don't exist in the following possibly-related books:
Player's Handbook (including II)
Dungeon Master's Guide (including II)
Complete Divine
Complete Champion
Libris Mortis
Rules Compendium
Spell Compendium
Unearthed Arcana

I just looked through a list of all of the Wizard's D&D 3.5 books. I've at least persed all of them, and I know of no rules that allow a cleric to change their deity.