It is apparent that Paul realized that he both “received” the Gospel through revelation and through the tradition imparted to him from his time with Peter. While this may seem like a contradiction, this is hardly the case. At the heart of Paul’s gospel is his own conversion experience. Obviously, we cannot know exactly what Christ said to Paul during that encounter on the Damascus road but we are certain that Christ revealed Himself to Paul. The simple act of revealing Himself to Paul is a dramatic revelation! Paul later travelled to Arabia where it is possible that he received additional revelation from Christ Himself.
Undoubtedly, Paul already knew a great deal about the teachings of Jesus. In my mind, it is difficult to believe that Paul, being such an adherent to the Law, would not have taken a keen interest in the way Christians were interpreting the Law since they believed that Jesus was the fulfillment of the Law being the Messiah. To Saul the Pharisee, this is blasphemy plain and simple. Paul’s assumptions were not only challenged, but also shown to be false, as he realized that what was happening was, in his own words, ‘a revelation of Jesus Christ’ (Galatians 1:12). The one whom Paul had so despised, and whose followers he was bent on punishing, was standing before him, thereby revealing his identity as Messiah, and inviting Paul to believe in him.
That said, there is still the matter of knowledge that Jesus had imparted to His disciples during His earthly ministry. While it is likely that Paul was aware of some, even many, of those teachings, the details were almost certainly missing. In his epistle to the Galatians (1:18-24), Paul tells of his 15 day stay with Peter and meeting with James. In fact, Paul clearly states that Peter and James are the only apostles with whom he met. During his stay, it is almost inconceivable that Peter did not share with Paul many of the details of his time with our Lord prior to His ascension.
Central to Paul’s gospel through revelation was his conversion experience on the Damascus road. In my opinion, only a meeting with the risen Lord would have been enough for Paul to accept that Jesus of Nazareth was in fact the Christ. This encounter with the risen Savior was a very personal experience that Paul could tell others about in great detail. Personal experiences can be very powerful, especially when sharing one’s faith with others. I can only imagine how powerful that testimony was during the many sermons Paul must have preached during his ministry!
Concerning tradition that was likely shared with Paul during his 15 day stay with Peter is that Christ dies for our sins in accordance with the scriptures, that Christ was buried, that He was raised on the third day in accordance with the scriptures, and that he appeared after His resurrection. In each instance, Paul uses the term “that” probably indicating that these were details that we already part of the Christian tradition that Peter shared with him.