In October 2012 the Holy See published the list of Equestrian Orders it formally recognizes.
“ It's a great honor to be named a Knight or a Dame in an Equestrian Order, but unfortunately, many people who claim to be part of these religious Orders are not.
To avoid misunderstandings, the Vatican has published the list of Equestrian Orders it formally recognizes.
On that list, are the Holy See's Equestrian Orders, which include the Supreme Order of Christ, the Order of the Golden Spur, the Pian Order, the Order of Saint Gregory the Great, and the Order of Pope Saint Sylvester.
In addition, there are two other Orders that are recognized and supported by the Holy See. These include the Sovereign Military Order of Malta, whose Grand Master is Fra Matthew Festing and the Equestrian Order of the Holy See Sepulchre of Jerusalem, led by Grand Master Cardinal O'Brien.
The list was published to make clear that the Holy See does not recognize the documents, insignias, membership or even diplomas issued by other Orders, who claim to fall under the protection of the Vatican. It's also a way to prevent the inappropriate use of sacred places, like churches or chapels for ceremonies of investiture.”