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Objective

In this lesson, we’ll discover how Paul’s inspired letters established the doctrinal foundation for the early church and continue to guide believers today.

Key Verse

Galatians 2:20: I have been crucified with Christ and I no longer live, but Christ lives in me. The life I now live in the body, I live by faith in the Son of God, who loved me and gave himself for me.

Introduction

The second half of Acts focuses on the extraordinary ministry of Paul. He became the most important teacher in the early church, and God used him in a remarkable way to bring correct doctrine and clear teaching to the growing Christian community. Through Paul’s writings, we receive half of the New Testament—thirteen powerful letters that continue to shape Christian belief and practice today.

Paul’s epistles were sent to specific churches facing real challenges or to specific individuals serving in ministry. These weren’t abstract theological treatises written in isolation, but practical, Spirit-inspired responses to the actual needs of first-century believers. Yet because they address the unchanging truths about God’s character and our relationship with Him, they speak just as powerfully to us today.

Paul wrote two types of letters. First, he wrote letters to churches: Romans, 1 and 2 Corinthians, Galatians, Ephesians, Philippians, Colossians, and 1 and 2 Thessalonians. Second, he wrote letters to individuals in ministry: 1 and 2 Timothy, Titus, and Philemon. Each letter was carefully crafted to meet specific needs while revealing eternal truths about our faith.

In this lesson, we’ll explore three important questions that will help us understand and appreciate these foundational books:

• Who was Paul and how did God prepare him for this ministry?
• What are epistles and why did the apostles write them?
• What are the main themes that run through Paul’s letters?

Who Was Paul?

Understanding Paul’s background helps us appreciate how God sovereignly prepared him to be the apostle to the Gentiles. We learn about Paul’s life both from the book of Acts and from personal details he shares in his own letters.

Paul’s original name was Saul, and before his conversion to Christ, he was a devoted and highly educated Jew. He had received the finest religious training available and was zealous for the traditions of his fathers.

Philippians 3:5: Circumcised on the eighth day, of the people of Israel, of the tribe of Benjamin, a Hebrew of Hebrews; in regard to the law, a Pharisee.

But Saul’s religious zeal led him in a tragic direction. He did not believe that Jesus was the promised Messiah, and this conviction drove him to become one of the most fierce persecutors of the early church.

Philippians 3:6: As for zeal, persecuting the church; as for righteousness based on the law, faultless.

The book of Acts tells us that Saul was present at Stephen’s stoning and that he “began to destroy the church” by going from house to house, dragging off men and women to put them in prison (Acts 8:1-3). This gives us a sobering picture of how religious conviction without truth can lead to terrible actions.

Everything changed when Christ appeared to Saul on the road to Damascus. In that dramatic encounter, the greatest persecutor of the church became its most powerful advocate (Acts 9:1-8). This transformation shows us that no one is beyond the reach of God’s grace, no matter how far they have wandered from His truth.

(Notebook Moment: How does Paul’s dramatic conversion encourage you when you think about people in your life who seem completely opposed to the gospel? What does his story teach us about the power of God to change even the hardest hearts?)

After his conversion, Paul received a specific calling from God to be the missionary to the Gentiles—the non-Jewish peoples of the world.

Galatians 2:7-8: On the contrary, they recognized that I had been entrusted with the task of preaching the gospel to the uncircumcised, just as Peter had been to the circumcised. For God, who was at work in Peter as an apostle to the circumcised, was also at work in me as an apostle to the Gentiles.

Paul completed three missionary journeys, establishing churches throughout the Roman Empire and training leaders to continue the work after his departure. Eventually, he was arrested in Jerusalem and sent to Rome for trial. Church history tells us that Paul was put to death in Rome during the reign of Emperor Nero, dying as a martyr for the faith he had once tried to destroy.

Paul became one of the most important figures in the early church. God used this former persecutor to write half the New Testament, giving us the clearest explanations of Christian doctrine found anywhere in Scripture.

What Are Epistles?

The word “epistle” simply means “letter,” and that’s exactly what these New Testament books are—letters written by the apostles to early churches and individuals to teach them and correct errors in doctrine. While these letters sometimes contained personal information like our letters today, they were far more than casual correspondence.

2 Timothy 4:13: When you come, bring the cloak that I left with Carpus at Troas, and my scrolls, especially the parchments.

Galatians 6:11: See what large letters I use as I write to you with my own hand!

These personal touches remind us that God inspired ordinary men like you and me to write the Bible. The apostles weren’t writing in some mystical trance—they were real people dealing with real situations, yet the Holy Spirit guided their words to give us exactly what we need for faith and life.

Sometimes the epistles address specific problems that existed in the early churches. Paul dealt with personality conflicts, moral failures, and doctrinal confusion with the same wisdom and grace that we need in our churches today.

Philippians 4:2: I plead with Euodia and I plead with Syntyche to be of the same mind in the Lord.

1 Corinthians 5:1: It is actually reported that there is sexual immorality among you, and of a kind that even pagans do not tolerate: A man is sleeping with his father’s wife.

2 Thessalonians 3:11: We hear that some among you are idle and disruptive. They are not busy; they are busybodies.

(Notebook Moment: Does it encourage or surprise you to learn that the early churches faced many of the same problems we encounter today? How does this help you understand that church conflicts and challenges are not new, and that God’s wisdom applies to every generation?)

Unlike our letters today, these epistles were inspired by God. While they addressed specific historical situations, their main purpose was to instruct the church in the doctrine and practice of our faith for all time.

2 Timothy 3:16-17: All Scripture is God-breathed and is useful for teaching, rebuking, correcting and training in righteousness, so that the servant of God may be thoroughly equipped for every good work.

Some of Paul’s epistles are more doctrinal in nature, focusing on deep theological truths. Books like Romans, Galatians, and Ephesians fall into this category. Others are more practical, teaching us how to live faithfully, how to endure persecution, and how to handle specific problems in the church. Examples include 1 and 2 Corinthians and 1 and 2 Thessalonians. But all of them blend doctrine and practice because what we believe about God should always shape how we live for Him.

What Are the Main Themes of Paul’s Epistles?

Paul teaches many vital truths in his letters to the churches, but three themes appear again and again as the foundation for everything else. Understanding these central doctrines will help you grasp the heart of Paul’s message and the core of the Christian faith.

➤ Law and Grace

First, Paul teaches clearly that we are not saved by keeping the law. We are saved by God’s grace through faith in Jesus Christ.

Ephesians 2:8-9: For it is by grace you have been saved, through faith—and this is not from yourselves, it is the gift of God—not by works, so that no one can boast.

Titus 3:5: He saved us through the washing of rebirth and renewal by the Holy Spirit.

The first epistle Paul wrote was Galatians, and its central theme is that the law cannot save us. Some teachers were telling the Galatian Christians that they needed to follow Jewish laws in addition to faith in Christ. Paul responded with passionate clarity that this teaching was not just wrong—it was a completely different gospel.

Galatians 1:6: I am astonished that you are so quickly deserting the one who called you to live in the grace of Christ and are turning to a different gospel.

Paul explained that trying to be saved by keeping rules actually nullifies the grace of God and makes Christ’s death meaningless.

Galatians 2:20-21: I have been crucified with Christ and I no longer live, but Christ lives in me. The life I now live in the body, I live by faith in the Son of God, who loved me and gave himself for me. I do not set aside the grace of God, for if righteousness could be gained through the law, Christ died for nothing!

➤ Justification by Faith

Second, Paul clearly teaches that we are made right with God through faith in Christ alone, not through our good works or religious efforts.

Galatians 2:16: Know that a person is not justified by the works of the law, but by faith in Jesus Christ. So we, too, have put our faith in Christ Jesus that we may be justified by faith in Christ and not by the works of the law, because by the works of the law no one will be justified.

Galatians 3:11: Clearly no one who relies on the law is justified before God, because “the righteous will live by faith.”

Paul gives Abraham as the perfect example of justification by faith. Abraham was made right with God not because of what he did, but because of what he believed.

Romans 4:1-3: What then shall we say that Abraham, our forefather according to the flesh, discovered in this matter? If, in fact, Abraham was justified by works, he had something to boast about—but not before God. What does Scripture say? “Abraham believed God, and it was credited to him as righteousness.”

This truth transforms everything about how we approach God. We don’t have to earn His acceptance through our performance—we receive it as a gift through faith.

➤ The Universality of the Gospel

Third, Paul teaches that the gospel is for everyone—not just for the Jewish people. As we saw in Acts, Paul was specifically called as the apostle to the Gentiles, and this message of universal salvation flows through all his writings.

Romans 10:12-13: For there is no difference between Jew and Gentile—the same Lord is Lord of all and richly blesses all who call on him, for, “Everyone who calls on the name of the Lord will be saved.”

Galatians 3:13-14: Christ redeemed us from the curse of the law by becoming a curse for us, for it is written: “Cursed is everyone who is hung on a pole.” He redeemed us in order that the blessing given to Abraham might come to the Gentiles through Christ Jesus, so that by faith we might receive the promise of the Spirit.

Ephesians 3:6: This mystery is that through the gospel the Gentiles are heirs together with Israel, members together of one body, and sharers together in the promise in Christ Jesus.

(Notebook Moment: How does it impact you personally to know that God’s salvation is available to everyone, regardless of their background, ethnicity, or past failures? How should this truth shape how we treat others and share the gospel?)

These three themes—law and grace, justification by faith, and the universal nature of the gospel—form the foundation for everything else Paul teaches. They are found throughout all his writings and provide the framework for understanding Christian doctrine and practice.

Conclusion

The epistles are both doctrinal and practical. They teach us what we should believe about Christ and how we should live for Him. Doctrine and practice should always be closely connected in the Christian life.

What we believe about Christ should determine how we live. Paul demonstrates this principle beautifully in his own testimony and teaching.

Galatians 2:20: I have been crucified with Christ and I no longer live, but Christ lives in me. The life I now live in the body, I live by faith in the Son of God, who loved me and gave himself for me.

2 Corinthians 5:17: Therefore, if anyone is in Christ, the new creation has come: The old has gone, the new is here!

The epistles provide the doctrinal and practical foundation for the church in every generation. Every believer needs to know these books well to grow in spiritual maturity and to be equipped for faithful service in God’s kingdom. As you continue studying these powerful letters, remember that they were written not just to inform your mind, but to transform your life through the truth of God’s amazing grace.

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