The Law of the Beast Folk symbolizes religion in human society. In fact, there's a slant of satire to the Law—that is, the Law is meant to mock religious rules and ceremony.
Moreau has become a sort of god figure for the Beast Folk, and it becomes super obvious when they chant stuff like, "His is the Hand that heals" (12.21) and "His are the stars in the sky" (12.24). The actual rules of the Law, such as "Not to chase other Men; that is the Law," have the vibe of the Ten Commandments to them (12.16). As for Sayer of Law, we picture him with a sort of Moses thing going on (but that might just be us).
All things considered, the religious satire makes sense historically. Wells's mother was domineering in her religious views, and Wells had a wee-bit of a rebellious streak in him. Also, Darwin's Theory of Evolution was still new and fresh in the Victorian mindset. People started to seriously question humanity's special, God-given place in the world and whether or not religion was still a legitimate source of morality and knowledge.
These questions were so difficult—and the emotions so strong—that the Victorians argued and called each other names over them ceaselessly. Heck, we're still arguing and calling each other names over them, and it's been over a century.
Still, even though this is satire, Wells was not anti-belief in God. As stated in his book The Invisible King, he had a "profound belief in a personal and intimate God." It's just that his understanding of the idea of God was complex and nuanced. He did, however, see the folly in how religion, particularly Christianity, tried to make out people to be something they aren't. As a scientist, Wells believed we are animals, and we came to be how we are today through evolution.
As a reader, it's important to realize that simply picking one side or the other—religion or science—isn't going to work when reading a Wells novel. And that's probably for the best. This is complicated philosophy after all; we shouldn't bet on it like it's the Super Bowl.