How would you go about, in the standard D&D world (with Clerical magic, etc.) designing a religious movement that in fact is not aligned with any god (not just, say, an evil cult pretending to be good or a chaotic cult pretending to be lawful or something like that)?  How would it be possible to 'fake' being a real religion with a real deity that has real clerics?

Magic items replicating clerical magic, or just a special wizard class representing someone stealing the secrets of divine magic. Eventually, establish the idea that the god/cult is strictly anti - magic, henceforth no divine magic - or restricted to only the most devout (in which case, again, enough little actual need for it that it can be replicated with some magical items - just stuff that Wand of Healing into your sleeve).

Or abolish the Clerical/Arcane magical divide in a setting and just let it roll.

Edition and setting elements matter, too. In several editions, you can TOTALLY have clerics with no discernable gods; clerics can connect to a philosophy or blend of ideas or whatever.

Well you could do it with wizards or you could do it with SCIENCE!

Black powder or electrical wrath of god, hot air filled "angels", telegraphic communion, germ theory and antibiotics might well pass for miraculous.

Heck you could even do the ultra tech society infiltrating the low tech world to direct their development.  Robotic beasts with feet of brass!

I could imagine something like Holy Texts that detail how priests commit themselves to their (fake) deity, that in actuality are training them in religiously flavored arcane magic, in addition to training them in other rites such as marriage ceremonies or whatever. Instead of believing they are learning magic "on their own", they believe they are learning to express the will of their deity. So, the religion has its tenets that would result in a priesthood consistent with both the religion and the limits of arcane casters. The spells available to the priesthood are taught in the holy text, and believing themselves to be holy men (and perhaps even [ironically] having a religious objection to the arcane), the idea of learning spells outside of their tradition would be unthinkable?

One approach might be to say that magic isn't ... ecumenical?  That is to say that the magic of the clerics of GodThingA is opaque to clerics of GodThingB. They don't understand each other's magic, even though they might recognize it after being exposed to it.

Along comes a group of wizards/sorcerers/whathaveyou, perhaps with an illusory bent, that set up shop as a new/old religion.

I typically think of standard D&D clerics as serving a single god, but this could work for multi-pantheon settings (e.g. Eberron ), but would work best in a lower-magic setting (e.g. NOT Eberron).

Haven't thought it through at this point, obviously, but I like the idea.

On the smaller scale, for a cult and not a large religion with many priests, I could imagine something like... a powerful creature who is not quite a god plays at being one. Something like a Djinni creates a holy text. It invisibly observes it's priest and uses its wish granting ability to perform religious miracles. The religion can be tailored to fit the abilities and desires of the powerful creature. If particularly limited, even another powerful wizard or cleric could serve the purpose of being this "fake god". The followers would not be insincere, only deceived.

Illusionists could probably do it. They couldn't heal people, but they could pretend to.

And then Druids don't worship any specific god, at least in D&D, so they could probably fake it.

And there are a number of semi-official classes on Dragon that can heal.

Darkness Gathering did that in a way I liked as a DM.

There was a cult in town, they were preaching something like the coming of the new masters or somesuch and were organized. But not sinister and generally seen as just kinda there, a little annoying in their eagerness. But the more you looked into it, the more you learned that things connected to the cult were not so nice.

Also an old module in Dragon had a monks monestary that had been taken over by a figure who turned them into a cult.

Currently in the campaign I am running the PCs keep bumping into an elven-supremacist cult whos goal is to kick out the non humans and return things to the "old ways". But are working through other cults to advance their goals.

One could even argue that, in AD&D, a Cleric of a "fake cult" would still be able to cast 1st and 2nd level spells as long as that Cleric was a true believer.

Justification for this position is from pg 9 of Deities & Demigods: "...1st and 2nd level spells are gained through the cleric's knowledge and faith.  All other spells are gained through prayer.  Third, fourth, and fifth level spells are granted by the supernatural servants or minions of the cleric's deity...Sixth and seventh level spells are granted to clerics directly from their deities."

One could argue that first and second level Clerical magic doesn't find its source in a particular deity or servant of a deity, but from the Cleric's faith and knowledge which tap into the "general" power of the aligned plane.  Only when granting of spells "gets personal" (i.e., 3rd level and above requiring the involvement of supernatural beings), is a specific deity or its servants necessary.

Also, I suppose it's not hard to imagine a lower-level supernatural being "standing in" or "posing" as a deity.  Or an actual deity posing and filling in for a nonexistent one.  An example of this might even be the Temple of Elemental Evil (Zuggtmoy the Demon Queen of Fungi using "elemental evil" as a more attractive front for her cult).

In my current campaign, there's a cult worshiping an ancient dragon. Not a demi-god dragon or anything, just a cruel, greedy and paranoid monster.

The sort-of twist is that they worship it not as a benefactor or anything, but because they fear and revere it. They offer it sacrifices and treasure (usually stolen from the rich people that they kidnap for said sacrifices). It all sounds awful, but it has been working: the villages have been safe from the dragon for many years.

And, inspired by Vornheim, the dragon allows some of the higher members of this cult to read the spells that are written in its scales. This grants them "powers" as a cleric.

All-in-all it's just fluff, but I'm having fun with it. The players think that they are just a run-of-the-mill dragon cult of evil.

In Red Shetland pretty much every cult and priest had no actual powers. But they did hope to attract the attention of whatever aspect they were following. So they werent worshipping for power. They were hoping for a actual visit. Which had a tendency to work about once a year when the stars were right. Temples were a rarity though. Usually personal projects. Outdoor festivals were more common.

Cults of personality though were more common. Good or bad. But often short lived. I based those around the ones Id seen flocking around popular artists at the time and extended it to things like musicians.

I think while setting and rule set is important it might be better to look at what a cult "Provides" that a religion or real church doesn't.

A certain level of inclusion and acceptance, a feeling of importance etc. You have to examine what the religions don't give and provide that. Cults in the real world don't provide miracles or "magic" they convince people they are the one true way, that what they do matters to the cult. etc.

If religion forces you to follow rules or worship certain ways then a cult would seek to undermine that and look for the fringes of society. People not saved by healing magic or too poor to tithe etc. A few fanatics can really make the difference starting a cult.

They can also always claim their faith is strong becuase their God doesn't provide convenient proof like curing a disease. He's gonna cure everyone that has faith now during the rapture, revelation, end of times or whatever.


So I think best cult leader, Evil Bard

In 5e there is enough overlap between the spell lists that wizards posing as clerics would be quite feasible. As long as you assume that magic is quite varied and not immediately recognisable as clerical or arcane, then it's cool.
Plus, who cares? They're baddies, they cast magic, yeeee ha!

Other than the bullshit concept that it's possible to be a legitimate cleric, with legitimate healing and blessing and clerical powers, just by hooking up with a "philosophical concept?"  (That being always, in my mind, a cheapass dodge for players who wanted to have the cool powers without having to follow any of those boring roleplaying constraints, follow any doctrine or dogma they didn't write themselves, or take a stand on anything.)

Easy.

I don't see, for instance, a single bit of difference, observable to a casual onlooker, between a priestess waving her hands in the air, shouting "May the great god Mitra grant us light!" and the room filling with light, and a wizard dressed in clerical vestments, waving her hands in the air, shouting "May the great god Bunsgrabber grant us light!" and casting a light spell.  If the paradigm of the common folk is that the gods grant their priests supernatural powers, well, a wizard can wear vestments, stand in a "temple" and work supernatural powers.

But, you say, how is the fake priest going to turn undead?  Easy.  "The great god Bunsgrabber is not a *weak* god, and He does not cowardly hope that the Unlife will just stay away!  This is how Bunsgrabber deals with the Unlife!"  Cue fireball hitting the zombie dead center.

But, you say, how is the fake priest going to heal people?  Easy.  For one, you deter the casual and the unfaithful.  "The great god Bunsgrabber is not a WHORE god like all the rest!  He grants healing only to His sincere worshipers!"  There in one fell swoop you take care of 90% of the supplicants.  For the handful you genuinely want to heal -- or the rich folk you want to think of themselves as True Believers -- just to make the scam look good, you invite them to drink from the Sacred Chalice upon which the Great God Bunsgrabber has breathed His mighty breath.  (Cue wind spell.)  That's the chalice you spike with a healing potion.

But, you say, how is the fake priest going to raise the dead?  Easy.  You don't.  "What is this blasphemy you speak?  Do you not know that the great god Bunsgrabber has vouchsafed your beloved dead a seat on His Great Comfy Waterbed, attended by the requisite seven Angels In Spandex?  How can you be so wicked as to wish them to return to this world of suffering and pot bellies?"