Paul did not just have a vision of Christ on the road to Damascus, he had a realisation that the time of the fullness of the gentiles was now. The promises to Abraham and the Prophets had been fulfilled, Israel was now many nations and his mission was to go to those nations and explain to them their true history.
This is borne out in his epistles, where he uses quotes from the Old Testament to show that the people he is talking to were the fulfilment of the covenants.
He was zealous for his kinsmen according to the flesh, but also for those other children of the promise who had forgotten the laws they had once held to, reminding them that they too had been under the cloud and with Moses, that they shared the same forefather and that the hopes of the fathers had now taken shape through Christ’s sacrifice and the growth of the nations in Europe.
Sven Longshanks and William Finck – Bible Basics Part 9