Originally called "Saul," Paul of Tarsus was a well-educated Jew. He had an early zeal for the law that led him to persecute Christians (Acts 8.3). He supported himself primarily by tentmaking. In the year 34, on the road to Damascus, he was converted by a vision of the risen Christ saying to him, "Saul, Saul, why do you persecute me?" (Acts 9) Paul's response was to develop into a dynamic missionary, beginning his travels twelve years later. As the center of the Jesus movement shifted from Jerusalem to the Mediterranean, many Gentile [=non-Jewish] converts to Judaism were receptive to Paul's preaching. Paul insisted that Gentile Christians and Jewish Christians are equal. He would preach and teach and organize Christian communities; he would stay in touch through letters and give guidance for the issues that divided them. Paul argued that Gentile Christians should be free to "live without the burden of the Torah and to enjoy an inclusive fellowship with Jewish Christians despite differences in lifestyle" (this quotation comes from--and most of the following paragraphs are based on--the Encyclopedia of Religion article on Paul by Robert Jewett). Paul was repeatedly embroiled in controversies, often violent, with political and religious authorities. He had great trouble with conservative opponents who insisted that even Gentile converts to Christianity had to submit to the full law of the Torah, including the requirement of circumcision.
Paul's missionary trips began around 46 CE into the northeastern Mediterranean, to cities in what is now Turkey and Syria. Sailing to Macedonia in 48, he spent time in Philippi and then went to Thessalonica, Beroea, Athens, and Corinth (where he returned in 56-57). He went to Jerusalem for an apostolic conference in 51 where the issue of Jewish requirements for Gentile Christians was hotly debated. (Paul's letter to the Galatians forcefully represents this debate.) From 52 for several years Ephesus (on the west coast of Turkey) was his home base. His letters from this period emphasize "resilient joy in the midst of tribulation." He goes to Jerusalem in 57, in preparation for sailing to Rome and on to Spain. He was imprisoned, however, arrived in Rome in chains, and was executed in 62.
Paul's letters were his way of staying in touch with congregations he had visited and nurtured, and his teachings reflect his responses to their specific issues. Robert Jewett summarizes some of Paul's teachings as follows. "Paul argues that men and women should retain culturally determined indications of sexual differentiation even while leading Christian worship, but he does not question the right of women to play an equal part." "Paul defends marriage as a permanent and mutual covenant to fulfill bodily needs." "The body [is] the basis of human identity and relationship." "The prideful wisdom that lay behind the competition among house churches in Corinth was contrasted with the word of the cross and the experience of humble hearers transformed by it." "All humans are equal in sin but also in unmerited grace." "The problem Paul finds with the Jewish law is that it lures humans into aggressive self-righteousness that produces death in place of life. True righteousness is the gift of God in Christ, inaugurating the new age of the spirit in which the good is accomplished . . . because it expresses the new status of belonging to "Abba, Father." Yet this new life occurs in the midst of a fallen world of decay, sin, and hostility, so faith is sustained by an eschatological hope in the triumph of righteousness by the ongoing experience of the love of God which death itself cannot thwart." Scholars agree that some NT letters--Romans, 1 Corinthians, 2 Corinthians, Galatians, Philippians, Philemon, 1 Thessalonians (also 2 Thess?)--are certainly his. Other letters attributed to him are disputed.
I would highlight the following themes from Paul's letter to the Romans. In order to know God it is not necessary to have special revelation. God can be known through creation (1.19-20). When the Gentiles act rightly they show that God's law is written on their hearts (2.14-15). Only faith in Christ, however, can liberate a human being from the power of sin (see chapter 3, where Paul sets forth the doctrine of the blood atonement). Paul's famous doctrine is that we are "justified by grace through faith." In other words, we are not "made right" with God ("justified") by works--by the things we can do on our own. It is God's gift (Latin gratia, grace) that justifies us. We can't earn our salvation by anything we can do. The righteousness that is required of us comes through faith. Only thanks to the transformation wrought in us by the Spirit of God can we love our neighbor (the summation of the law; 12.1-2; 13.8-10). "For the kingdom of God is not food and drink but righteousness and peace and joy in the Holy Spirit" (14.17). "To God be the glory."
There are two ways to live: according to the flesh or according to the Spirit. Knowing the law is not sufficient for righteousness, since the "flesh"--the self dominated by material emotions--wars against the Spirit. "The wages of sin is death--but the free gift of God is eternal life in Christ Jesus our Lord." (Chapter 6)
Who are the family of God? "All who are led by the Spirit of God are children of God. For you did not receive a spirit of slavery to fall back into fear, but you have received a spirit of adoption. When we cry, "Abba! Father!" it is that very Spirit bearing witness with our spirit that we are children of God." "I am persuaded that neither death, nor life, nor angels, nor principalities, nor powers, nor things present, nor things to come, nor height, nor depth, nor anything else shall be able to separate us from the love of God." (Chapter 8; Mt. 23.9; Gal. 4-1-7).
Galatians highlights: "There is no longer Jew or Greek, there is no longer slave or free, there is no longer male and female; for all of you are one in Christ Jesus" (3.28). "For you were called to freedom, brothers and sisters; only do not use your freedom as an opportunity for self-indulgence, but through love become slaves to one another. For the whole law is summed up in a single commandment, "You shall love your neighbor as yourself" (5.13-14). "The fruit of the Spirit is love, joy, peace, patience, kindness, generosity, faithfulness, gentleness, and self-mastery" (5.22-23). "Bear one another's burdens" (6.2). "Do not be deceived: God is not mocked, for you reap whatever you sow" (6.7). "Whenever we have an opportunity, let us work for the good of all, and especially for those of the family of faith" (6.10).
Additional quotes. "Do not be conformed to this world, but be transformed by the renewing of your minds, so that you may discern what is the will of God--what is good and acceptable and perfect" (Ro 12.2)
"In him we live and move and have our being" (Ac 17.28)