The Peaceful Paradise Cult is a cult/religion started by Harimoto Takashi.
The Peaceful Paradise spoken of in the title refers to a world in which all demons are wiped from existence. These demons reside in our world and look just like humans, but are much more sinister, indeed. They can brainwash humans into committing crimes such as murder and rape. One can expel the demon from their body by joining the cult and chanting certain holy incantations.
As they believe, Humans were once very pure and noble creatures, who did not fight with one another. However, soon the demons arrived and, upon mating with humans, their genes spread like wildfire. Of course, the amount of demon genes varies from person to person. Those more than half demon are referred to as Devil Dominant, and they are the ones that make up criminals and scam artists, and as such, there are many Devil Dominant people in the Liar Game. Devil Recessive refers to the people whose demonic genes take up much less of a percentage. The goal of the Peaceful Paradise Cult, therefore, is for the Recessive humans to breed together and have children with lower and lower percentages of demonic genes, eventually wiping them out all together.
One is able to tell at a glance who is Dominant and Recessive with the proper training. The one closest to being pure-blood human is Harimoto himself, as he only has a few percent of demon genes still lingering in his body.
The members define their rank by the number of years they believe themselves to have lived.