Question:
Answer:
The Roman Martyrology (RM), so titled, was first published in 1583. And though it may have been given a quasi-“official” status in the sixteenth century, it can no longer be considered as such.
Pope St. Pius X established the Acta Apostolicae Sedis in 1909, preceded by the Acta Sanctae Sedis, which was established in 1865 as the only “official” publication of the Holy See.
But, most importantly, even in the sixteenth century, the RM was never considered magisterial. It was and is a historical work. It does not concern matters of faith or morals. This should be made quite clear when considering that it was revised first in that same year of 1583, and then in 1584, 1586, and 1589 by Caesar Cardinal Baronius. He was asked to do so by the Holy See, and he had help.
In 1630, the RM was revised by Pope Urban VIII, and then by Pope Benedict XIV in 1748. Each one of these editions added new saints or martyrs and also provided corrections. All involved knew that these histories are not immune from legends, exaggerations, and even just plain errors, that need to be excised.
Then, at Vatican II, the council fathers ordered another revision that explicitly aimed to eliminate legends and unsubstantiated claims. This was published in 2001 after many years, and the RM was republished in 2004. “Pope” Felix II is nowhere to be found in these revisions.
Why? The history of antipope Felix is a complicated, and began after the true pope at the time—Pope Liberius—was exiled, imprisoned, and tortured by the Arian Emperor Constantius II in 355 for refusing to sign an Arian creed. The antipope Felix was most likely either an Arian himself or extremely favorable toward the heresy, because otherwise the Arian emperor Constantius II would not have had him installed as a pseudo-pope. He was illegally (and invalidly) installed as bishop of Rome. And he was not “martyred” (a heretic can’t be a true martyr anyway); he died quietly in exile in A.D. 365.
Felix was later confused with a true saint and third-century martyr by that same name, and, at times, with a later true Pope Felix. That is how his local legend grew. However, it must be noted that there were always questions about the veracity of the story. Even Cardinal Baronius himself wanted to remove him from the RM, but it would be Pope Pius XII who would set the record straight in 1947, when he listed him as an antipope in the Annuario Pontificio; and so he was removed from the Roman Martyrology as well. The Annuario Pontificio, too, is not magisterial, but it is the Vatican’s go-resource for the history of popes.
As far as the decree of Pope Gregory XIII is concerned, it did not—and could not—include future popes among those excluded from modifying the RM, because in the law of the Church “equals cannot bind one another” in non-infallible matters.