About Paul's letter to the Romans

Paul wrote this letter when he was staying in the city of Corinth. Corinth was in the south part of the country that we call Greece. Paul wrote this letter about the year AD 57. That was about 30 years after Jesus died.
Paul wrote this letter to the Christians who were living in the city of Rome. Rome is the capital of the country that now we call Italy. At the time when he wrote this letter, Paul himself had never visited Rome. But he hoped to go there soon. Nobody knows how the church at Rome started. Perhaps people had travelled from Rome to Jerusalem, the capital city of Israel. Perhaps they had heard the good news about Jesus in Jerusalem. See Acts 2:10. After they had gone back to Rome, they told the good news to people there.
Some of the Christians at Rome were Jews. Some of them were Gentiles. See Romans 1:13. There may have been problems between the Jewish Christians and the Gentile Christians, because they thought about things differently. They may have been meeting in separate groups, in different places. So Paul knew that he had to explain his message to both Jewish Christians and Gentile Christians.
Paul himself was a Jew. Many years before, God had given his Law to Israel's people. God gave those rules to them because he wanted them to be his own special people. He wanted them to obey him. God had not given those rules to the Gentiles. But some Jewish Christians thought that Gentile Christians should still obey those rules.
So, in this letter, Paul writes about the purpose of the rules that God gave to Moses for his people. Those rules were very good and very important. They helped Israel's people to obey God. But Paul explains why those rules could not save people from their sins.
In Romans 1-8, Paul explains that all people, both Jews and Gentiles, as they are born, cannot make God happy. All people need to become right with God. Only God can do that. We need God to save us from our sin. If we believe that Christ died on our behalf, on the cross, God accepts us as right with himself. Then, by God's Holy Spirit, we become united with Christ. In this way, we become new people who can be God's friends.
In Romans 9-11, Paul writes about Israel's people (the Israelites). They are the special people that God chose to belong to him. Many of them have refused to believe in Christ, but God has not turned away from them completely. Paul knows that God still wants them to trust Jesus as his special Messiah.
In Romans 12-16, Paul describes how Christians should live their lives in this world. It is important that Christians love each other and other people.