Circles can do amazing things when they intersect to have sex. The ancient sects of Gnosticism loved their diagrams, riddles, and mathematics; they worshiped knowledge. Jewelers often pose their marriage rings; in such a way, to create a symbolic intersection. Two intersecting circles or rings create a child; it even has a name – Vesica Piscis. The Vesica Piscis translates to fish bladder.and alludes to the womb.
Pagans used the Vesica Piscis as a symbol for fertility, but the Gnostics used it for something more. Valentinianism uses male/female pairs; they call syzygies. I suspect the Gnostics were the ones who created the Ichthys, some call it the Jesus fish, and if you look close—I outlined it in red.
Early Christian inscription with the Greek letters “ΙΧΘΥΣ” carved into marble in the ruins of the ancient Greek city of Ephesus at Turkey
Wikipedia goes on further about the Ichthys, but it is obvious the wheel, in the image above, symbolizes ‘eternity.’ Jesus caught 153 fish and that number relates to the Vesica Piscis. The Flower of Life is also formed from intersecting circles and cam easily symbolize fertility. My chapter in rewrite features Baubo (Iambe) and Sheela Na Gig; which, relate to the womb and thusly the Vesica Piscis.
Giving my fictional fertility cult multiple roots allows for more flexibility. The Inquisition punished those who strayed from Catholic thought, so it was difficult for other beliefs to survive, in the Western World. I see it as plausible for some fertility rituals to survive, as fringe Christianity. Other cultures added their own elements and reinforced lingering aspects of fertility rites.