Grand Grimoire: The Gospel of Satan

The Grand Grimoire, also known as the ‘Red Dragon’ or the ‘Gospel of Satan’, is a medieval artifact believed to possess immense powers. It was written in the 16th century by Honorius of Thebes, who claimed to be possessed by the devil himself. In the book, it has instructions on how to make magic talismans and amulets, how to make magic spells, and even how to summon demons. However, most alarmingly, it even offers instructions as to how to summon the devil himself and make a deal with him. There have been many copies made after the original was published, however, only the Vatican has the original, unaltered copy. Some claim that the others are fake, or have been altered to make them worthless. Others claim that all copies have some power, but the original copy owned by the Vatican is the most powerful. Still, according to some, the only real, functional copy is held by the Vatican as a way to protect humanity from unimaginable carnage if the book fell into the wrong hands.

Image Credit: http://controversialfiles.blogspot.com/2013/01/the-grand-grimoire.html

One version of it claims to date to 1522. Its full title is The Grand Grimoire, with the Powerful Clavicle of Solomon and of Black Magic; or the Infernal Devices of the Great Agrippa for the Discovery of all Hidden Treasures and the Subjugation of every Denomination of Spirits, together with an Abridgment of all the Magical Arts. The editor, Venitiana del Rabina, said he translated the work from the writings of Solomon himself, which came into his possession. 

The Grand Grimoire is divided into two books: 

The first book contains instructions for summoning a demon and for the construction of tools with which to force the demon to do one's bidding. 

The second book is further divided into two parts: 

1. The Sanctum Regnum - contain instructions for making a pact with the demon, allowing one to command the spirit without the tools required in book one, but at greater risk. 
2. Secrets, de L'Art Magique du Grand Grimoire ("Secrets, of the magic art of the Grand Grimoire") - contains simpler spells and rituals one can employ after having performed the ritual in the first book 

Some editions contain a short text between these two parts, Le Secret Magique, où le Grand Art de pouvoir parler aux Morts (The Magic Secret, or the Grand Art of being able to speaking with the dead), dealing with necromancy. 

This book mentions three higher demons: Lucifer (emperor), Beelzebub (prince), Astaroth (grand duke). These demons are similarly prioritized in Grimorium Verum. Although, in Tarl Warwick's English translation of the work, the "demons" are referenced by the more generic term of "spirits."

Sources:

• https://en.wikipedia.org/wiki/Grand_Grimoire

• https://listverse.com/2020/05/04/top-10-things-possibly-hidden-in-the-vatican-secret-archives/

• https://www.ancient-origins.net/artifacts-ancient-writings/gospel-satan-grand-grimoire-one-creepiest-medieval-manuscripts-out-there-021709

• http://controversialfiles.blogspot.com/2013/01/the-grand-grimoire.html

• https://occult-world.com/grand-grimoire/