Saint Paul was born at Tarsus in Cilicia, of a father who was a Roman citizen, and into a family in which piety was hereditary and which was much attached to Pharisaic traditions and observances. As he belonged to the tribe of Benjamin he was given at the time of his circumcision the name of Saul, which must have been common in that tribe in memory of the first king of the Jews. As every respectable Jew had to teach his son a trade, young Saul learned how to make tents or rather to make the mohair of which tents were made. He was still very young when sent to Jerusalem to receive his education at the school of Gamaliel. Possibly some of his family resided in the holy city; later there is mention of the presence of one of his sisters whose son saved Saul's life. From that time it is absolutely impossible to follow him until he takes an active part in the martyrdom of Saint Stephen. He was then qualified as a "young man," but this was a very elastic appellation and might be applied to a man between twenty and forty.
Paul's experience on the road to Damascus is recounted in the Acts of the Apostles, as we heard in this morning's First Reading. Throughout his own writings Paul refers to his sudden conversion as an unforeseen, sudden, startling change, due to all-powerful grace. In his letter to the Galatians, Paul states, I would have you know, brethren, that the gospel which was preached by me is not man's gospel. For I did not receive it from man, nor was I taught it, but it came through a revelation of Jesus Christ. For you have heard of my former life in Judaism, how I persecuted the Church of God violently and tried to destroy it; and I advanced in Judaism beyond many of my own age among my people, so extremely zealous was I for the traditions of my fathers. But... He who had set me apart before I was born ... called me through His grace and was pleased to reveal His Son to me.
To Timothy Paul explains that he obtained this mercy because he had acted in ignorance: I received mercy because I had acted ignorantly in unbelief, and the grace of our Lord overflowed for me with the faith and love that are in Christ Jesus. Paul tells the Corinthians: Have I not seen Jesus our Lord? He appeared to me last of all, as to one untimely born. For it is by the grace of God I am what I am, and his grace toward me was not in vain.
Thus a blasphemer and a persecutor was made an apostle, and chosen to be one of the principal instruments of God in the conversion of the world. Saint Paul never recalled to mind his wonderful conversion, without raptures of gratitude and praise to the divine mercy. The Church, in thanksgiving to God for such a miracle of His grace, from which it has derived such great blessings, and to commemorate so miraculous an instance of His almighty power, and to propose a perfect model of a true conversion has instituted this festival, which we find mentioned in several calendars and missals of the eighth and ninth centuries, and which Pope Innocent III commanded to be observed with great solemnity. It was for some time kept as a holy day of obligation in most churches in the West.
Adapted from F. Prat, "Saint Paul," Catholic Encyclopedia, vol. XI, 1911, and Butler, "The Conversion of Saint Paul," Lives of the Saints.