help I have to make a whole new religion

Sigh... I'm back here again with my homebrew campaign that continues to make problems for me, but I love it too much to stop. Basically, I need a religion, and it can't be one of the usual ones, so, uh, if any of you have any spare religions stored away somewhere, I would give you 20 bucks and a tub of rocky road to be able to use it. I am entirely willing to give credit if you want it. Hell, if you guys even know any websites that might have religions I could use, I would be so grateful.

Oof homebrew worlds are tough. I’m running a campaign with one right now, and I’m STILL editing the lore. You didn’t specify what kind of religion so I’ll give a couple evil and good ones

1. The Order of Eversleep

Worships whatever demon or Archdevil you have with sloth (if you don’t have one, mine is Zeeriaz). They use magic powder that puts people into an eternal coma, pushing their souls into the Dream Realm where (insert Archdevil) reigns supreme, keeping them there with their worst nightmares and best dreams. They are silent, moving town to town, knocking out bystanders and sending them to their master. This one can either be a side quest or a campaign, depending on the usage.

2. The Poet’s Followers

Worships either Apollo or some other musical/poetry god/goddess and creates hymns and other such arts to worship their god. Typically composed of bards and clerics. They have no overarching goal other than to spread worship.

3. The Order of Vigilance

An order of heroic paladins and other such fighters whose goal is to kill demons and ask questions later. They also fight other evils, but main goal is to keep demons in the underworld. They typically have outposts near portals to wherever you have demons live in, and temples/compounds within large cities; containing a small militia of them. They mostly worship war gods (Bahamut for me).

I’ll try and think of some more soon

Sorry, I should have specified, but I'm looking more for a pantheon? I'm not sure if you have one of those ready lmao, I expect most people don't. This world (it's called Solstara, just for future reference on this thread) already has a main religion, but it wasn't the original religion and isn't true. It's called the Pythium Orchaia, and it's run by a singular corrupt leader whose held the city for probably several hundred years. There was a religion before this, but I'm not quite sure what to make it. There are no current worshippers of the original religion.

If you're looking for a pantheon, you could just take a look at some of the officially published settings and their pantheons and just repurpose for your own uses. Forgotten Realms has MASSIVE amounts of lore related to the deities. The Exandrian deities also have a decent amount of lore, and there's far fewer of them than FR. Or take an actual polytheistic religion from the real world, like the Ancient Greek or Roman deities, or the old Celtic gods, and rename/repurpose them for your world.

If you really want to create your own, start with the major domains and go from there: Sun, Moon, Life, Death, Law, Chaos/Trickery, Nature, Magic, etc. And some evil domains for Undeath, Tyranny, Murder. Come up with names and short bits of lore, and why they are no worshippers of this original religion anymore. If there's no active worshippers, you don't need a lot of lore about it, unless the old religion is a major part of your campaign. 

The easy way is to just take a real-world religion like the Greek pantheon, change the names and other identifying details, and call it done.

A not much harder way is to just take the major domains of any real-world pantheon (storm, trickster, mother, father, farming, death, love, music, cheese, etc.), divide them up fairly arbitrarily among a bunch of names, make up some connections (X and Y are the original creators of the world, A, B, C, D, and Q are their kids. Z, the trickster god, is X's brother, and never gets invited to parties anymore, etc. etc.)

But the real question is: how much detail do you actually need? It's really very unlikely that the players will be getting into the deep theology. Depending on their role in the campaign, you may need as little as "there are old gods". Even if you do need more detail, you can probably make it up on the fly.

Honestly, if the original religion is functionally dead, its exact details probably don't matter very much unless you plan to make it a plot point, and if you do plan to make it a plot point, you want to design it around the needs of your plot, so people on the internet who don't know what you're trying to do won't be terribly helpful.

Most fantasy religions are nonsensical anyway, real religions tend to be complicated, often contradictory, and contain a wide variety of elements that are thoroughly irrelevant to your average D&D campaign. There's some advice in the 2014 DMG about creating pantheons, though it's pretty limited.