I'm writing my own D&D universe and there are two deities I've chosen from the official setting to incorporate: Lolth and the Cat Lord
The Cat Lord seems to be depicted as a deity for the Tabaxi in Volo's Guide to Monsters. I've tried to find more information about the church of the Cat Lord, how they work, their beliefs etc. but I haven't found anything.
Where can I find more information about the Cat Lord, especially focusing on mortal worshipers (organization & hierarchy, rituals, worldview, etc.)?
Best Answer
The Cat Lord is not a deity
Until the 5th Edition Volo's Guide to Monsters, none of the many variations of "Cat Lord" in D&D canon rose past rank 0 "quasi-deity," and even that was only a sidebar'd suggestion in the Epic Level Handbook.
In terms of religious veneration of the Cat Lord, the best attestation I could find came from Dragon Magazine Compendium, in which the tibbits are also said to follow the Cat Lord. Here, the Cat Lord is identified merely as "a powerful creature" and it's noted that the tibbits have no organized religion surrounding her, viewing her as more of an older brother figure and spiritual protector. This includes no details about any religious practices.
...but the tabaxi have other gods
The gods of the tabaxi, at least in the Maztica setting, are Tezca, Nula, Azul, and Zaltec.
Tezca is a chaotic evil solar deity. He desired fresh human hearts as sacrifices. His faith is a brutal one; each day at sunset, his priests congregate to offer the fresh heart of an unfortunate victim to ensure that the sun-god shall show his face again tomorrow. His faith is related to warmth, life, and power over fire.
Nula is a chaotic neutral goddess of wild beasts, a demipower whose influence is growing slowly across the Maztican continent. She is invoked by hunters and those who fish, leaving gifts of seed and bone in the wilds for her to know she has been called upon. Primarily depicted as a monkey, she has lesser aspects representing many other animals of the wilds.
Azul is a lawful evil god of water and rain. Often the first deity enshrined and venerated in new territory (to ensure the rains favor this land and will provide for its people), Azul watches over all bodies of water, from the smallest streams to the mighty ocean, and even the very rare (in tabaxi territories) snowfalls. His priesthood keep themselves scrupulously clean with baths and pumice stones. Foul sacrifices are performed to him in the spring to ensure a prosperous wet season.
Zaltec is a chaotic evil war god, a vicious deity symbolized by skulls, hearts, blood, and jaguars. Tabaxi who have fallen under the sway of a tabaxi lord (a related creature) tend to worship Zaltec. He is venerated by fresh hearts on his altar, blood spilled in battle, fasting, and ritual scarification. His priests wear black robes, wash their hair in the blood of their victims, and spike it outward in garish diplays. What that might look like, who could say.
Beyond that, though, there is nothing official about the Cat Lord's religion
...because, as noted above, it simply doesn't exist. "Cat Lord" is a well-worn trope in D&D, having appeared in some form in short stories (a group of them appear), novels, the 1st Edition Monster Manual II (the original, a male), Planescape (the second, a female), the Epic Level Handbook (a 37th-level shapeshifting rogue, male) and elsewhere on and off. Until Volo's Guide, however, none firmly attributed deity status to a Cat Lord, and no source that I've found suggests any kind of open worship.
That doesn't mean you can't borrow some...
There are other feline deities, of course - you can look into Ferrix, goddess of weretigers; Bast, a vengeful Egyptian tutelary cat goddess, and Sharess, a Faerunian demipower of cats and hedonism. Any of these might provide a reasonable model for a Cat Lord religion, if that's what you're after.
I hope this has helped.