Originally Posted by LilyM
, it was simply the evidence of his actual existence was reexamined and found a little lacking - this happened to a number of other saints, including Nicholas of Myra (better known as Santa Claus)
not quite, the actual formal process of canonization was not in place before the 11th century, when the canon, or list of saints was first drawn up and the process for declaring saints was prescribed. Before that saints were usually a local affair acclaimed and affirmed by the faithful and bishop of the diocese for their piety, martyrdom etc. What happened after V2 when the canonization process was revised, also the Roman canon, the list of saints and their prescribed feast days to be observed by the universal Church also changed. Some saints like Nicholas that used to have a universal feast day were changed to optional memorials. They still have a fixed feast in countries where they are patrons. These are saints for whom we do have historical basis for their lives and works. This is to make room on the calendar for memorials for saints with local significance as patrons of countries, dioceses, cities. So each country has their own calendar in addition to the universal Roman calendar. So Saint David has a feast in Wales, for instance.
Some saints of the early Church that have been venerated due to long tradition but about whom we actually know and have documented very little were also removed from the universal canon, but that is not to say they are not saints, just that they do not have an assigned feast day. Faithful can still venerate these saints, such as Christopher and Philomena but they are not listed in the canon. That is not the same as saying, sorry, we blew it, this guy is not a saint never was never has been.