In my previous post, I shared insights on the meaning of this beatitude that were unique to John Wesley and Dietrich Bonhoeffer. Now I would like to share an insight that is common to both.
Both Wesley and Bonhoeffer view mourning as including what we might describe as a “missional” or “evangelistic” dimension. Disciples will mourn for the world.
Bonhoeffer: “Such [disciples] mourn for the world, for its guilt, its fate and its fortune.”
Wesley: “…yet is there another, an a blessed mourning it is, which abides in the the children of God. They still mourn for the sins and miseries of mankind: they ‘weep with them that weep.'”
Here we find an insight that speaks to the deep need we have for an inside-out transformation of the heart. Another Englishman, G.K. Chesterton once remarked that Original Sin was the only Christian dogma that did not require faith, just newspapers. Who can take the frustration, anger, and disdain understandably directed at ample evidence of sin and injustice in the world but those whose hearts the Spirit of Christ has convicted, humbled, comforted, and transformed?
Justice demands that we mourn (and are appropriately angry too) for the one who has been harmed. But this teaching reminds us that the one who harms has, while harming another person, harmed their own soul as well. And for what is done to every soul—without losing track of who is victim—disciples will mourn.
In this, we imitate our Lord who looked upon Jerusalem and mourned, as recorded in Luke 13:34:
Jerusalem, Jerusalem, you who kill the prophets and stone those sent to you, how often I have longed to gather your children together as a hen gathers her chicks under her wings, and you were not willing.
Sharing in Christ’s mourning for the sin, guilt, and rebellion of the world, we share also in receiving the comfort he alone can provide and pointing others to our comfort in him.
Because of this capacity to join the heart of Christ in mourning missionally and evangelistically, in Bonhoeffer’s words, “Nobody loves his fellow-men better than a disciple, nobody understands his fellow-men better than the Christian fellowship, and that very love impels them to stand aside and mourn.”
Guy M Williams 
Guess you could also call this a “just mourning”, for Jesus was mourning not only what Jerusalem had done, but what was to come as well. When does a hen cover her chicks with her wings? In times of direct threat, even fire. Then hen sacrifices herself to protect her chicks. Jesus likewise was mourning that Jerusalem was not accepting his offer to be sacrificed on its behalf, but instead subjecting itself to the wrath of God’s justice!
(“just mourning” TM Jay Lopiccolo, 5 Feb 2015)