Paul's Sainthood
Question
When was Paul canonized by the Church?
Answer
In the modern Roman Catholic Church there is only one way to achieve "official sainthood" -- canonization. However, this was not the only method before circa 950AD. Prior to this, there were two ways that one could achieve official sainthood: through martyrdom, and through the public acclamation of the faithful. The date recognized by the Roman Catholic Church for the martyrdom of St. Paul is 67AD with no month or day specified. Thus, 67AD is the date for his official recognition as a saint.
The 29th of June is the day that has been chosen, according to the Catholic Encyclopedia, "from time immemorial" to observe the martyrdom of Paul (this, interestingly, is also the date for the observance of Peter's martyrdom). The 25th of January is a date that has been "comparatively recently" chosen as the day on which to celebrate Paul's conversion.
So, in summary, Paul was never canonized, because he was officially recognized as a saint prior to the advent of official canonization. History does not record exact dates for his conversion or martyrdom, so each of the dates discused here is speculative, to a degree. January 25 is the date his conversion is celebrated, June 29 is the day his official sainthood is celebrated. June 29 is historically more reliable and is more relevant to the discussion of canonization.
Answer by Matthew Gross