"Resist him, standing firm in the faith, because you know that your brothers throughout the world are undergoing the same kind of sufferings." NIV translation
We are not alone in facing the enemy as we know that all of the world Christians are being attacked. We stand on the fact that God is with us as well.
"And the God of all grace, who called you to his eternal glory in Christ, after you have suffered a little while, will himself restore you and make you strong, firm and steadfast. To him be the power for ever and ever. Amen." NIV translation
We are called to be with God forever but our time here on earth can be a struggle. It is a struggle here because the whole world has the bad effects of sin in it. God has the power to overcome sin and restore us and keep us forever.
"With the help of Silas, whom I regard as a faithful brother, I have written to you briefly, encouraging you and testifying that this is the true grace of God. Stand fast in it." NIV translation
It all comes down to grace and Peter sums up his letter by reminding us of that fact. He encourages us to stand on that grace and not try to add anything else to it as that is the entire basis of our salvation.
"She who is in Babylon, chosen together with you, sends you her greetings, and so does my son Mark." NIV translation
Peter closes his letter here by passing on greetings from some of the fellow workers for the kingdom. It is interesting to not that one of them is a woman from what we call Iraq today.
"Greet one another with a kiss of love. Peace to all of you who are in Christ." NIV translation
Peter closes by instructing us to greet each other. This is to remind us that we are one in Christ and that we should care for each other. He then leaves us with peace and it is just for those who are in Christ because without Christ it is impossible to have peace.