"'Blessed are the peacemakers, for they will be called children of God.'" NIV translation
What is a peacemaker? It is one who promotes peace by telling others about Jesus Christ who is the ultimate source for peace. There are many people these days promoting a man-made "peace" but think that it is achievable if God is left out of it. A true peacemaker knows that Christ is the Prince of Peace and is recognized as a child of God.
"'Blessed are those who are persecuted because of righteousness, for theirs is the kingdom of heaven.'" NIV translation
Persecution is a type of testing which proves what is in our hearts. This is talking about those that are punished and even killed for telling others about Jesus Christ. When faced with the choice of keeping our faith to ourselves or sharing it and facing the earthly consequences, those who share it demonstrate that their kingdom is of heaven.
"'Blessed are you when people insult you, persecute you and falsely say all kinds of evil against you because of me. Rejoice and be glad, because great is your reward in heaven, for in the same way they persecuted the prophets who were before you.'" NIV translation
Rejoicing when you are being attacked is not a normal reaction but it is a characteristic of those who are close to the kingdom of heaven. We are blessed when this happens because it can be a confirmation that the world sees that you are a child of God. Only those that are identified in Christ will be a part of the kingdom of heaven and we can be happy when even the world sees that we are His.
This verse completes the section of the sermon that is commonly called "The Beatitudes" and we notice that there are nine times that the word "blessed" is used. Throughout the Bible, the number nine is associated with finality and judgment. We are reminded that these characteristics of people of the kingdom will be demonstrated during the Millennial Reign. This will be a time of demonstrating that, even without the influence of Satan, man cannot live up to these standards on their own. After the Millennial Reign comes the final judgment.