Paul used what Christians referred to as the Old Testament to splendid effect as a theological resource. The New Testament and the Old Testament are two books whose writers were inspired by God; thus, one cannot be seen as different from the other since they cannot be separated. After all, the Old Testament has its revelations in the New Testament. To early Christians, arguments were strange, as they could not imagine the teachings of Paul and other Apostles on the same level as the Old Testament teachings. Paul is a comprehensive teacher of the gospel as postulated by the Epistles in the New Testament. Paul uses these letters used to spread the gospel to the many tribes of Israel and the whole world. Roman is one such epistles sent to the Romans to offer them spiritual direction. In the letter of Paul to the Romans, Paul cites abundantly from the Old Testament to convey his message.
James Gregory, Jesus, Paul and the Gospels. (WBE Publishing Company, 2011), 16-35.