"Blessed are the peacemakers, for they will be called children of God." (Matthew 5:9) (NRSV)
Blessed are the "eirenopoioi"--the makers of peace. I sometimes think this the most challenging of all the beatitudes.
Consider the historical context. Simon "the Zealot" was among the closest followers of Jesus, and Judas may have been a Zealot, or at least sympathetic to their position. Peacemaking was not part of the Zealot's agenda, though perhaps they might have said, "We shall have peace. We shall have peace when every Roman is dead or driven from our land, and when those who cooperated with the Romans have been punished." By saying these words, Jesus took a position within the complicated political life of the time. Obviously, peacemaking does not require that everyone agree with or like the peacemaker's position. Ironically, peacemaking may well put one at odds with others or a group!
Many evangelical Christians tend to restrict the beatitude's application to interpersonal relationships. The historical context disallows such a limit. At the very least, the beatitude was a political statement. Followers of Jesus, by implication, are called to be voices for peace and workers toward peace in the world of politics. Christian advocates for war (even "just war")are hard put to justify their position, let alone investing their life resources in such a way.
Jesus claimed to reveal the nature of the rule of God, the kingdom of God, and so the very priorities of God. Peacemaking is a top agenda item with God, indeed part and parcel of the character of God. Using God's name, therefore, to invoke or justify violence, division and war may well amount to taking the Lord's name (character) in vain.
Peacemaking is not restricted to the political arena. Interpersonal relationships do come into play. Reconciliation is the life work of a Christian. I use the term "work" intentionally. Peacemaking should not be confused with passivity, "going along to get along," or the like. It requires active engagement in the lives of others. Theologically, the Incaranation underscores God's commitment to reconciliation and calls Christians to join in God's work.
The sixth beatitude's promise is that such peacemakers shall be called or recognized as children of God. On the one hand, the promise offers a bit of comfort as we struggle to "make peace" in a divided world. The promise also suggests that peacemaking is the mark or identifying characteristic of a genuine follower of Jesus. So much for going to war (in any fashion) over creeds and the like, as if discerning and adhering to just the right formulas marked one as a genuine follower of God.
"The devil is in the details," I suppose. It's one thing to embrace all the above in general, quite another thing to practice peace-making with regard to particulars. It's much like the well-worn (but quite accurate)saying with regard to love: "I love humanity, it's people who give me trouble." Still, I see no way out. To follow Jesus well requires that we become and remain peacemakers.