Paul's Theology of Being Made Right with God Through Faith in Jesus Messiah
Paul's opening statement in Romans tells us about the power that literally propels him to proclaim Jesus to the Gentiles.
In verse one he definitely asserts that he is someone who is sent by another. In his case he is not just a messenger, (apostolos in Greek) but he is a Apostle. He intends the use of a capital "A" meaning that he is a messenger called and sent by God. Chapter 1:1. Paul is a messenger by compulsion.
To put a double underscore to his motivation Paul regards himself a servant (literally a slave) of Jesus Messiah and as Jesus' slave Paul testifies to the outstanding qualities of his master.
Jesus Messiah is a master worthy of Paul's total loyalty. Paul is not merely a disciple, not merely a messenger but literally Paul has no choice but to be an Apostle sent to tell about his master.
He has no choice because Jesus is both Son of David according to the flesh and Son of God according to the Spirit. Jesus is the Christ (Messiah) and therefore, Paul's master (Lord).
This Jesus was announced to Mary by an Archangel before his conception, Luke 1:31-35, was acknowledged as Lord by Elizabeth Lk 1:43, was heralded by the heavenly host, Lk 2:11, and witnessed to by Simeon, Lk 2:26-35 and Anna Lk 2:38.
As servant of Jesus, Paul's apostleship is focused on calling people from among all nations to become obedient to Jesus- a Jesus further validated as Master through the resurrection of Jesus from the dead.
Paul regards this call as a gracious invitation of a loving and universal God- a God from the Jews but not exclusively of the Jews. This universal God is a god whose nature is unmerited loving kindness- a kindness revealed to us by God's inclusive embrace of his created children as their Father. Romans 1:5-7