Matthew 5:4 meaning

The parallel account of this teaching is found in Luke 6:21.

Jesus's statement (B), Makarios are those who mourn for they shall be comforted, corresponds with (B') Makarios are the peacemakers, for they shall be called sons of God (vv 4, 9).

The second line of Jesus's chiasm is also paradoxical. In the first statement the servants are the rulers in the kingdom of heaven. Jesus now says that Makarios (happy and fulfilled) are those who mourn (v 4). Mourning is an outpouring of grief and sorrow. Mourning is typically associated with the opposite of happiness or fulfillment (Makarios). It results from being profoundly disappointed with surrounding circumstances.

What then does Jesus mean when he says that Makarios are those who mourn? (v. 4)

This is likely a zooming in of the attitude already introduced. To become poor in spirit requires that we recognize our neediness, and to empty ourselves of the deception that we are self-reliant. It requires we see our limitations with the eyes of reality. It requires us to see our inherent sinful state. To see ourselves as we actually are. When we see ourselves truly, it ought to lead us to mourn because we fall so far short (Romans 3:23). This mourning is the mourning of self-awareness. It is the setting aside of rationalizations and comparisons to other people, and recognizing our standing in the sight of God, our Creator.

An example might be a painful realization someone has when they recognize that much of their life has been a mistake. Mourning is a sign of regret and disappointment. It is an integral part of changing perspectives from what is not true to what is true. It leads to repentance, which begins with a change of heart. When people recognize that they have been chasing the wrong pursuits, deeply investing themselves in finite things (i.e. earthly kingdoms), and by extension have not invested themselves in what is good, true, and eternal, mourning is a proper response.

But Jesus consoles those who mourn (in this life), for they shall be comforted (v 4). Having repented of self-reliance and self-deception, they are now free to live in reality. They can now seek the Kingdom of God and His righteousness. This provides great comfort, because it makes the pain worthwhile. The agony of seeing our own neediness opens the door for us to reach the fulfillment (Makarios) for which our souls long.

Those who mourn their sinful condition have rightfully recognized that the Kingdom of Heaven is at hand and repented (changed their ways). The rewards they will receive in the kingdom of heaven shall be their comfort. This promise is in future tense. The sufferings they endure and mourn in this life shall be redeemed into a great comfort for them when the Messiah's kingdom is fully realized (Romans 8:18, 8:28, 2 Corinthians 4:16-18). While this promise is future tense in this passage, it is also a comfort in this life, through the eyes of faith that the promise will be fulfilled (2 Timothy 1:12).

Contrasting those who mourn are those who elevate self. People who pretend they are better than they are. This leads to division and coercion. It creates tyranny of one person over another, in defiance of God's reign. It is rooted in a demand for control. The irony is that those who seek to rule will not rule in the kingdom that is to come, and those who serve others shall inherit the right to reign in harmony with God. Those who mock God shall reap what they are sowing, which will include dissension and strife. This will not lead to fulfillment (Makarios).