Obedience to the Law is now obedience to Christ.
Blessed/Happy
5:3 The Greek word for happy (makarios) denotes blessedness or happiness not in the sense of an emotional state but in terms of being in a fortunate situation
In the Jewish tradition, beatitudes either commended those who take a certain path of life or promised future consolation to those in affliction (see Biblical Background sidebar).
Ultimately the beatitudes are nothing less than a portrait of Christ’s own life. Matthew depicts Jesus as meek (11:29; 12:15–21; 21:5), merciful (9:27–31; 15:22; 17:14–18; 18:33; 20:29–34), and persecuted (27:27–31, 39–44). As an indirect portrait of Jesus, the beatitudes “display the mystery of Christ himself, and they call us into communion with him.”
5:4 How are those who mourn to be considered happy? In this beatitude, Jesus does not commend mourning as such but praises those who grieve over wickedness, whether it be afflicting others or causing them suffering directly (Tob 13:14; Isa 61:2; Ezek 9:4). From a worldly standpoint, these mourners appear to be quite unhappy. But Jesus says they are truly in a good situation because, although they may not be able to change the circumstances around them, they can resist evil internally by mourning it. Moreover, they can have confidence that God will vindicate the faithful and that they will be comforted. This comfort belongs also to those who repent and mourn for their own sins (Ps 51) and to those who, like Daniel and Ezra (Dan 9:1–19; Ezra 9:5–15), mourn for the sins of God’s people
inherit the land. In Ps 37, this is a reference to the promised land. Jesus uses the image not geographically but spiritually as referring to the kingdom
Since the peacemakers share in the Father’s mission of reconciling the world to himself (2 Cor 5:19), they shall be called children of God—a title that points to the intimate relationship Christ’s disciples will have with God, who, Jesus repeatedly tells them, is “your heavenly Father” (5:16, 45, 48; 6:1, passim).