In the Kingdom and the Exile
The Law, the sign of God's promise and covenant, ought to have governed the hearts and institutions of that people to whom Abraham's faith gave birth. "If you will obey my voice and keep my covenant, . . . You shall be to me a kingdom of priests and a holy nation." But after David, Israel gave in to the temptation of becoming a kingdom like other nations. The Kingdom, however, the object of the promise made to David, would be the work of the Holy Spirit; it would belong to the poor according to the Spirit.
Source: Catechism of the Catholic Church (Vatican.va)