He reminds them of what they already have--a new birth into a living hope through the resurrection of Jesus Christ. He offers them reassurances that God will continue to protect them.
But, as we read these reminders and reassurances, we also realize the reason Peter offered them--They were undergoing suffering because of their faith.
Peter's explanation for the suffering is that it is necessary so that their faith may be found genuine. Suffering helps us get rid of the unnecessary and focus on the important. For example,
See, I am sending my messenger to prepare the way before me, and the Lord whom you seek will suddenly come to his temple. The messenger of the covenant in whom you delight--indeed, he is coming, says the Lord of hosts. But who can endure the day of his coming, and who can stand when he appears? For he is like a refiner's fire and like fullers' soap; he will sit as a refiner and purifier of silver, and he will purify the descendants of Levi and refine them like gold and silver, until they present offerings to the Lord in righteousness (Malachi 3:1-3).
Many Christians during Lent do a kind of purification, choosing to eliminate certain foods or distractions from their lives so that they can focus more on what is really important. I'm wondering whether we have picked those habits back up now that Lent is over or whether we have now become a new kind of Christian.
Peter says to them to rejoice. Their new faith that has come through the period of testing, will be genuine and will result in praise and glory and hone when Jesus Christ is revealed.
Reading these words from Peter (or as my Bible commentaries lead me to believe, someone else for whom the early church put Peter's name on his letters), I'm wondering how applicable they are for me. I know that in some parts of the world that Christians are under attack. But where I live they really aren't. What is it that I have to give up in the world that I live because I am a Christian? Am I suffering because of it?
How genuine is my faith? How much of my life, how many of my decisions are based on example of Jesus Christ?
Can I discern what is important? Can I tell the difference between the gold and what should be refined away?