"Blessed are the peacemakers, for they shall be called sons of God." (ESV)
"The peacemakers are blessed, for they will be called sons of God." (HCSB)
"How blessed are those who make peace, because it is they who will be called God’s children!" (ISV)
"Blessed are the peacemakers: for they shall be called the children of God." (KJV)
"Blessed are the peacemakers, for they shall be called sons of God." (NASB)
"Blessed are the peacemakers, for they will be called the children of God." (NET)
"Blessed are the peacemakers, for they will be called children of God." (NIV)
"Blessed are the peacemakers, for they shall be called sons of God." (NKJV)
"God blesses those who work for peace, for they will be called the children of God." (NLT)
"Happy the peacemakers -- because they shall be called Sons of God." (YLT)
I've listed ten different translations of this verse to show that they all say basically the same thing. We will be blessed by God when we live as people who make peace. This does not suggest that we earn God's favor by being peacemakers, but it does make it clear that God is pleased by this behavior. He also expects it.
But what does Jesus mean by being peacemakers?
I've heard this verse misinterpreted many times by well-meaning (and usually military supporting) evangelicals. Far too many of these folks say that Jesus is mainly referring to helping others make peace with God by accepting the gospel. This verse amounts, in this view, to another Great Commission. While sharing our faith is certainly important, neither the context of this passage nor the specific wording indicates that Christ has this in mind here.
Why would these evangelicals misinterpret this passage in this way? The reason is that they, ironically, fear the idea of peacemaking in its most basic sense. I'm referring to helping others live lives of day-to-day peace with other people through turning the other cheek and loving enemies. These truths, while spoken by Jesus in this very chapter, are not popular in much of American Christianity. They fly in the face of the military aggression that is so prevalent in our society and which is so often supported by the church.
In Matthew 5:9 Jesus is not talking about assisting lost people in coming to peace with God through the gospel. Rather, Jesus is telling his soon to be followers that he expects them to live peacefully in an unpeaceful world. He expects them to not retaliate when wronged (look at 5:10-12). Jesus desires that his people promote peaceful, kind, non-aggressive interactions among others. While the world wages war, Christ's people are to be agents of peace.
Let's be those people of peace that Jesus is talking about in the Beatitudes.