Children of Maira

The tribe of Maira is an ancient civilization worshiping The Maker. The civilization originated as a megachurch of radical extremists pushing the agenda of The Maker.
The sigil originated as a horned feline-like two-faced beast, possibly shown in variations with and without a serpent-like tail. Later incarnations of this tribe have also adopted an unusual ouroboros in the shape of an infinity symbol (also possible with a Möbius strip twist).
The actual sigil of recent iterations may be a merge between the original beast and the ouroboros.
The church was formed before the first division of the Inlanders vs. Outlanders, adopting the motif that despite the separation between the people, all should be united under the guidance of The Maker. And the Church views those who do not worship The Maker as inferior in mind and body. Thus, various rituals to "cleanse" others include extreme measures such as an obsolete version of lobotomies (for both cleansings of the body and mind), psychological tortures (mind), and physical mutilations (body).
The Church became an underground organization as more Outlanders adopted to worship the All-Mother instead, viewing her as a more benevolent force and the Inlanders refusing to bow to religion.
The harmful nature of this Church has marked it as a threat to civilization as they viewed themselves as above the law, above morality, and humanity. Thus, the Church has been marked as a pariah of the old world and forced to "disband" (i.e. tried and prisoned for various war and terrorist crimes).
In the current understanding of the world, with the death of Dr. Tobias Sable (as a pillar that upholds the world and separates The Maker's realm/influence is shattered), leaving a crack to allow for the evil forces of The Maker to seep through. Therefore descendants of the Church took this opportunity to reform the church under a new disguise hoping to harness the power of The Maker, left behind by Dr. Sable.
They reformed as the Dahlia Agnus Congregation (DAC) (pretending to bear the mark of dahlias), led by Reverend Sonnik Daye. They carried on the ritualist sacrifices of the old church to gain favor with The Maker and to borrow his powers to enslave the world (only those high within the Congregation, such as Reverends hold powers of The Maker).

Additionally, an early form of DAC attempted to sacrifice an early form of Dr. Calliope, believing her to be an reincarnation of the All-Mother, the torture she underwent corrupted her mind and somewhat inspired her to form Chimera Inc. Thus, the Church of the Children of Maira (at least in part) is also thought to serve as a major predecessor for Dr. Calliope's formation of Chimera Inc.