Romans 1:1 Paul, a servant of Jesus Christ, called to be an apostle, separated unto the gospel of God,
We see that Paul names himself the writer of this epistle. It is an important distinction to make that he was the writer, not the author. The Spirit of God was, in actuality, the author. Paul was the means by which the words inspired by the Holy Spirit were penned so that we could read them today. He was called to be an apostle. Look in Acts 8 of the story of his travels on the road to Damascus.
Acts 8:1 And Saul, yet breathing out threatenings and slaughter against the disciples of the Lord, went unto the high priest, 2 And desired of him letters to Damascus to the synagogues, that if he found any of this way, whether they were men or women, he might bring them bound unto Jerusalem. 3 And as he journeyed, he came near Damascus: and suddenly there shined round about him a light from heaven: 4 And he fell to the earth, and heard a voice saying unto him, Saul, Saul, why persecutest thou me? 5 And he said, Who art thou, Lord? And the Lord said, I am Jesus whom thou persecutest: it is hard for thee to kick against the pricks. 6 And he trembling and astonished said, Lord, what wilt thou have me to do? And the Lord said unto him, Arise, and go into the city, and it shall be told thee what thou must do. 7 And the men which journeyed with him stood speechless, hearing a voice, but seeing no man. 8 And Saul arose from the earth; and when his eyes were opened, he saw no man: but they led him by the hand, and brought him into Damascus.
Was Paul, then Saul, looking for Christ? Was Paul seeking after the Lord? You could argue yes, to persecute Him. We see the sovereignty of God here. God came to a man in His own time and in His own way. It is the same for all of us. We have no power to seek God, and in fact we hate the true God. Paul persecuted Christ until the time it pleased Him to reveal Himself to Paul. This was not by the choice of Paul but by the will of God. By the will of God Paul was called to be an apostle.
John 15:16 Ye have not chosen me, but I have chosen you, and ordained you, that ye should go and bring forth fruit, and that your fruit should remain: that whatsoever ye shall ask of the Father in my name, he may give it you.
John 6:44 No man can come to me, except the Father which hath sent me draw him: and I will raise him up at the last day.
Philippians 3:4 Though I might also have confidence in the flesh. If any other man thinketh that he hath whereof he might trust in the flesh, I more: 5 Circumcised the eighth day, of the stock of Israel, of the tribe of Benjamin, an Hebrew of the Hebrews; as touching the law, a Pharisee; 6 Concerning zeal, persecuting the church; touching the righteousness which is in the law, blameless. 7 But what things were gain to me, those I counted loss for Christ.
Look at the credentials Paul could boast of. He was a pharisee among pharisees. All this he counted as nothing as he had been called out. He was called to serve the living God and to repent and believe on the name of the Lord Jesus Christ.