What does Matthew 5:4 mean?

At the beginning of the Sermon on the Mount, Jesus is teaching a series of statements often referred to as the Beatitudes. Each starts with the words "blessed are." Blessing, in this sense, refers to a declaration of what is good and why. It does not mean that the blessed person will feel happy, necessarily.

The difference between happiness and being "blessed" is especially obvious in this verse. This beatitude states that those who mourn are blessed. Those who mourn, by definition, are not happy. Jesus wants His followers to understand that those who experience mourning are not hopeless.

Within the context of Jesus' teaching about the coming kingdom of heaven, those who mourn may do so because of their own sin or because of the sin of Israel. The Jewish people experience a state of mourning under the harsh oppression and occupation of Rome. Those faithful to God and Scripture understood this to be a result of Israel's sin and unfaithfulness, since God had promised to prosper them when they were faithful and to judge them when they were not.

Both John the Baptist and Jesus preached that Israel must repent. Repentance involves sadness as we recognize and confess our sinful selfishness. Those who mourn while repenting of their sin are blessed, however, because the kingdom of heaven will come; they will be rescued. The season of judgment will end.

Not all commentators agree that Jesus is referring only to mourning that comes with repentance from sin. Much sadness in life, of course, is not the result of sin. It comes from living on a planet ruled by death. Of all who mourn, those in Christ are blessed because they will be comforted by God in the here and now (2 Corinthians 1:3–7) and free from mourning for eternity (Revelation 21:4).