Matthew 28
Union with Christ — Dying and Rising in Romans 6
Sanctification flows from union with Christ. Rom 6:1-11 argues that those baptized into Christ were baptized into his death, so that "we too might walk in newness of life." Sin's dominion is broken because the believer has died and risen with Christ. Calvin made union with Christ the center of applied salvation, holding justification and sanctification to be distinct but inseparable gifts received in the one Christ. The same union grounds the Catechism's theology of life in Christ and the Eastern vision of the sharing in the divine life that Athanasius described. Owen developed the believer's mortification of sin from this union. The baptismal logic of 6:3-4 connects to the Great Commission of Matt 28:19 and to the new-creation theme of Rom 8:1-4, where there is now "no condemnation." Sanctification is the outworking of a gift already given.
The Virgin Birth — Isaiah 7:14 and Matthew 1
Matt 1:22-23 reads the birth of Jesus as the fulfillment of Isa 7:14: "the virgin shall conceive and bear a son, and they shall call his name Immanuel." Matthew hears in Immanuel, "God with us," the whole meaning of the incarnation. Irenaeus saw the virgin birth as the new beginning of humanity, Mary undoing the knot of Eve. Aquinas defended its fittingness: the new creation requires a new origin. The sign given to faithless Ahaz becomes the sign to the world. The Immanuel theme frames the whole Gospel, returning in Matt 28:20, "I am with you always." It connects to the Word made flesh in John 1:14 and to the protoevangelium's promised seed in Gen 3:15.
The Trinity in the Great Commission — Matthew 28:19
Matt 28:18-20 commissions the church to baptize "in the name (singular) of the Father and of the Son and of the Holy Spirit." One name, three persons: the baptismal formula is implicitly trinitarian. Augustine's On the Trinity mined this text for the unity of the divine persons, and the Nicene Creed gave the church its trinitarian grammar. Basil and the Cappadocians defended the Spirit's full deity on such baptismal grounds. The baptism commanded here is unfolded theologically in Rom 6:3-4, and the abiding presence of 28:20 echoes the Immanuel of Matt 1:23. The triune name is the church's confession and its commission.
Baptism into Christ — Romans 6 and Matthew 28
Rom 6:3-4 interprets baptism as union with Christ's death and resurrection: "we were buried therefore with him by baptism into death, in order that... we too might walk in newness of life." The sign signifies a real participation. Calvin defined a sacrament as a visible word that seals the promise, and the Catechism treats baptism as the gateway to life in the Spirit. Augustine's debates with the Donatists shaped the church's theology of valid baptism. Baptism is commanded in the Great Commission of Matt 28:19 and grounded in the union of Rom 6:5-11. It is the visible entry into the body addressed in 1Cor 12:13.