Hungering and thirsting is a characteristic of the poor and in Luke Jesus refers to the literal hunger and thirst of those living in poverty. Similar to the first beatitude, scholars will often wrestle with the original form of the saying. The consensus opinion is that Jesus referred to literal poor people who were hungry and Matthew expanded the saying to refer to spiritual hunger.
In the Matthew form of the saying, Jesus adds “for righteousness,” perhaps thinking of passages such as Psalm 42:1, “as a deer pants for the water.” This metaphor appears frequently in Wisdom Literature for one who is pursuing righteousness. But it is important to define righteousness in the context of Second Temple period Judaism.
Like each of the beatitudes, “hungering for righteousness” can be turned into some inner pursuit of holiness or seeking a state of sinlessness. But as Scot McKnight rightly points out, there are two nuances of righteousness in Greek. In some contexts the word refers to a righteous behavior, such as an act of righteousness. For a Jewish listener, to pursue righteousness would be covenant faithfulness, keeping the Law with very real, concrete actions. For example, in Acts 10 an angel commends the God-fearing Gentile Cornelius for his acts of righteousness. These acts include “gave alms generously to the people, and prayed continually to God” (Acts 10:2). In the Second Temple book known as the Psalms of Solomon, the one “who does righteousness stores up life for himself with the Lord” (Psalm of Solomon 9:5).
But in other contexts, especially in Romans and Galatians, righteousness refers to the state of the believer who is in Christ. Paul gives this word an additional theological meaning in the New Testament. In Galatians 3:6 Paul uses righteousness to describe the state of the believer: they have been declared righteous on the believer in Christ, making him righteous. This is the crux of salvation, moving the believer from death to life. And Paul is quite clear obedience to the Law is not why God declares a person righteous. Although it is very difficult to do the reader of the Sermon on the Mount needs to check their Pauline theology and try to head the words of Jesus in a Second Temple period Jewish context. As a side note, this will also help with the so-called disagreement between Paul and James.
What is Jesus talking about when he says his true disciples will hunger and thirst for righteousness? If Jesus’s original audience heard echoes of the Hebrew Bible, the acts of righteousness are meeting the needs of the literal hungry and thirsty. Looking ahead to the conclusion of the other “sermon on a mount,” Matthew 25:34-40 says the true disciples of Jesus will be taking care of those who are hungry and thirsty, caring for the lowest members of their society. This does not mean a follower of Jesus can give up on pursuing personal holiness, but Jesus’s point is the one who does real holiness is going to hunger for feeding the hungry, etc.
Those who pursue righteousness will be satisfied. The verb (χορτάζω) is used for being physically satisfied with food (as in the feeding of the 5000 in Matthew 15:33, “sated” or “bloated,” McKnight, Sermon on the Mount, 44), but is sometimes used for spiritual satisfaction (Psalm 17:5).
Hunger and thirst are also associated with the coming Kingdom of God (Isa 25:6-8). In the eschatological age God will invite all people to his mountain and serve them a grand meal of the best meats and finest wines. This eschatological banquet inaugurates an ideal period of peace and prosperity when even the final enemy Death is destroyed. As with the other beatitudes, this saying looks forward when God will enter history and establish a kingdom ruled by a righteous king, Jesus.
Perhaps this beatitude is one of the easiest to fined contemporary application since poverty is a serious problem in most of the world. In the context of Matthew 5, however, the follower of Jesus is called to meet the needs of other Jesus followers. This is consistent with the first few beatitudes which described the followers of Jesus as poor and humble.