1 Peter is a letter in the Bible's New Testament. The author of the letter is Peter. Peter was a disciple (student) of Jesus. And Peter became a leader in the first Christian church, in Jerusalem.
Peter wrote his letter to Christians who were suffering great troubles. Peter wanted them to trust God more. Their troubles would test them. But they were joyful, even when they suffered. They were joyful, because they trusted God's promises. And they were joyful, because Jesus died for them.
So, Peter encouraged them to be holy. Their troubles would last for a short time. But God's word lasts always. And they will always live with God in heaven. There, they will not suffer.
God chose them to be his people (1 Peter 2:10). So, they were special people. They did not belong to this world (1 Peter 2:11). They belonged in heaven.
Jesus suffered many terrible things, too. But he did not reply when people insulted him. He did not complain. He trusted God. And when Jesus died, he suffered the punishment for our evil deeds. This was how he made us into the people of God (1 Peter 2:21-25).
We should copy Jesus, even when we suffer. We should respect our husbands and wives (1 Peter 3:1-7). We should respect our employers (1 Peter 2:18-21). And we should even respect rulers and governments (1 Peter 2:13-17). They might be evil. But we should still be good. We should tell them gently about Jesus (1 Peter 3:15).
We might suffer because we are Christians. But even if this happens, we should be glad. And we should praise God that we are Christians (1 Peter 4:12-19).
Peter advised these Christians to love each other (1 Peter 4:8). And, he had special advice for the church leaders (1 Peter 5:1-4).