Then he was a liar. He said he saw the risen Lord.
1 Cor. 15:4-8, And that he was buried, and that he rose again the third day according to the scriptures: And that he was seen of Cephas, then of the twelve: After that, he was seen of above five hundred brethren at once; of whom the greater part remain unto this present, but some are fallen asleep. After that, he was seen of James; then of all the apostles. And last of all he was seen of me also, as of one born out of due time.
Do you need someone to diagram those sentences for you? Paul saw Christ in the same manner as the other Apostles. If he did not see the resurrected Christ, then he was a liar. There is no getting around it.