The first four Beatitudes are variations on the theme of lacking something, with the fourth referencing those who hunger and thirst after righteousness. The poor in spirit, those who mourn, the meek and the hungry — are all in need of what Jesus offers. But, the deficiency is less important than the awareness of the condition. While the first four Beatitudes do indeed offer resolution of a problem through salvation, they also require the Christian to perceive their circumstances.
Just like the poor in spirit — who recognize their debts can be paid by grace — the hungry and thirsty know that “man shall not live by bread alone.” When Jesus was tempted by the devil in Matthew 4:4 and said those words, he was harkening back to Deuteronomy 8:3 where Moses reminded the Israelites that it was God who provided manna but that man doesn’t live from bread only.
The first half of Beatitudes teach a singular truth: we can’t achieve the ultimate satisfaction — eternal salvation — without Jesus.
6 Blessed are they which do hunger and thirst after righteousness: for they shall be filled.