From Wikipedia
From The MysticaGyromancy is a method of divination in which a person spins around inside or walks the circumference of a circle drawn on the ground, the perimeter of which is marked with the letters of an alphabet. The divination is inferred from the letter at the position where the person either stumbles or falls across the circle’s edge. The person would repeat the practice "...till he evolved an intelligible sentence, or till death or madness intervened."[1] The dizziness brought on by spinning or circling is intended to introduce randomness or to facilitate an altered state of consciousness.[2]
The word is derived from Medieval Latin, gyromantia, which is derived from Greek gyros (circle) and manteia (oracle).[3]
A method of divination by going around in a circle which circumference was marked with letters of an alphabet. The presage evolved as words formed from the letters onto which the inquirers stumbled when becoming too giddy to stand up.
There is a curious connection between the practice of this divination and the familiar technique of psychic circles. In this practice all siting in a circle place a finger on a glass surrounded by letters of the alphabet. The glass will touch letters in turn to indicate words or messages.
The principle of the repeated circling is to exclude the interference of the will so to reduce the selection of letters to mere chance. In few species of enhancement, however, the art of turning round is to induce prophetic delirium. Some religious dances, particularly the rotation of certain devotees on one foot with arms out stretched, are of this nature. Such incidents indicate a sort of mystical secret.
Another form of gyromancy is where the person walks around in a circle until the individual collapses. The position that the person falls in relation to the circle determines the outcome of future events.
In the phenomenon known as the St. Vitus' Dance manifestations of spirit intelligence were observed the movements of those in convulsions. The action of the spiritual force tends to be spirally rhythmically, whether in language or bodily members. A.G.H.
Now, we know that the Cult has gotten eager, or giddy, to resurrect their God during the time of Silent Hill 1. This is evident by how Dahlia decided to resurrect God early, not waiting for the actual "due date" that was predicted long ago. Dahlia decided to use Alessa, but she somehow knew that Harry Mason would come.
"It was foretold by Gyromancy."
This could point to the fact that even more rituals (mainly originating from Europe) could have been in the Order as well. From the links and the text above, Gyromancy is a method of Divination (telling the future).
This also points to the fact that Dahlia might not have done this, but some past Order member long ago- perhaps there were other attempts (aside from the obvious ones past Dahlia) that involved other rituals other than the Immolation Ritual (that's what I call it), even to the point of telling the future.
So, in short, there has been previous attempts at resurrecting God and predicting certain dates of Cheryl and Harry's arrival, to the point of classical Divination rituals performed, leading up to the point of Dahlia finally predicting Harry's actions and manipulating him.
A little penny for your thoughts
Please point me out if there are any holes.