Is there any account of how Paul learnt Jesus teachings after he converted?
Jesus revealed to him that the Christian heresy was actually true, and inspired him to properly understand and believe what he already knew but could not accept.
At the time of Saul's conversion, the Greek scriptures, what we call the New Testament, hadn't been written yet.
All references to "scripture" within the New Testament are to the Hebrew scriptures.
Acts 8:25–40 tells of how Philip taught the Gospel:
- [The Ethiopian] was reading Isaiah the prophet …
- Philip … said "Do you understand what you are reading?"
- Then Philip opened his mouth, and beginning at this Scripture, preached Jesus to him.
The Apostles relied upon the Hebrew scriptures to teach the message of the Gospel.
Saul, as a defender of the faith, had to be very familiar with the scriptures.
Acts 8:1–3, 9:1–3 describes his persecution of the new Christian sect:
- Now Saul was consenting to [Stephen's] death.
- At that time a great persecution arose against the church which was at Jerusalem; and they were all scattered throughout the regions of Judea and Samaria, except the apostles.
- As for Saul, he made havoc of the church, entering every house, and dragging off men and women, committing them to prison.
- Then Saul, still breathing threats and murder against the disciples of the Lord, went to the high priest
and asked letters from him to the synagogues of Damascus, so that if he found any who were of the Way, whether men or women, he might bring them bound to Jerusalem.
Saul was very familiar both with the scriptures and with Christian heresies.
Saul had an encounter with Jesus, as described in Acts 9:3–9:
- suddenly a light shone around him from heaven.
- Then he fell to the ground, and heard a voice saying to him, “Saul, Saul, why are you persecuting Me?”
- And he said, “Who are You, Lord?” Then the Lord said, “I am Jesus, whom you are persecuting.
- So he, trembling and astonished, said, “Lord, what do You want me to do?”
Acts 9:15–16 says that Jesus had chosen Saul for a special purpose:
- he is a chosen vessel of Mine to bear My name before Gentiles, kings, and the children of Israel.
- For I will show him how many things he must suffer for My name’s sake.
Jesus chose Saul because of his knowledge and dedication.
Following his realization that the Gospel of Jesus was not heresy, Saul quickly absorbed any details he hadn't previously known from the disciples, as described in Acts 9:19–22:
- Then Saul spent some days with the disciples at Damascus.
- Immediately he preached the Christ in the synagogues, that He is the Son of God.
- Then all who heard were amazed, and said, “Is this not he who destroyed those who called on this name in Jerusalem, and has come here for that purpose, so that he might bring them bound to the chief priests?”
- But Saul increased all the more in strength, and confounded the Jews who dwelt in Damascus, proving that this Jesus is the Christ.
Saul now used his existing knowledge of scripture and Christian doctrine to promote Christianity, with the same dedication and determination that he had previously used to persecute it.