Next Sunday is the celebration of Ascension Sunday in most dioceses of the United States. You can read a complete commentary on the Gospel here.
16 The eleven disciples went to Galilee, to the mountain to which Jesus had ordered them. 17 When they saw him, they worshiped, but they doubted. 18 Then Jesus approached and said to them, “All power in heaven and on earth has been given to me. 19 Go, therefore, and make disciples of all nations, baptizing them in the name of the Father, and of the Son, and of the holy Spirit, 20 teaching them to observe all that I have commanded you. And behold, I am with you always, until the end of the age.” (Matthew 28:16-20)
In the Gospel according to Matthew, this is the first scene in which disciples have appeared since they fled during the arrest of Jesus (26:56). Since that point in the narrative, Jesus has been crucified, died and laid to rest in the tomb. In the verses just before our text, the tomb has been just found empty by the faithful women who reported that an angel of the Lord and Jesus himself has appeared with a message for the “eleven disciples.” Presumably the disciples are following the message of Jesus, delivered by the women, to meet Jesus in Galilee. Thus, the disciples are not acting based on their own witness to the risen Christ, but upon the testimony of others. It is by that witness that the disciples take their next step on the journey of faith. Thus, there is already a nascent belief in the Resurrection, even if they do not yet fully comprehend the implications and consequences of that salvific act.
That sets the immediate context of our passage. But there is a larger context in play. R.T. France [1987, 417] writes that these final verses of Matthew 28 serve to complete the framework of the entire Gospel.
First, v. 18 presents Jesus as the universal sovereign. In 1:1–17 he was presented as the successor to royal dignity, and 2:1–12 portrayed him as the true ‘king of the Jews’. So in due course he entered Jerusalem as her king (21:1–11), but it is this very claim which has brought him to the cross, where it was mockingly displayed (27:37). But now the promise of chs. 1–2 is proved true after all, and on a far wider scale than a merely Jewish kingship, in ‘the enthronement of the Son of Man,’ whose rule is over ‘all nations’ (v. 19), indeed over both heaven and earth (v. 18). Secondly, and still more wonderfully, 1:23 presented Jesus the baby under the name ‘God with us’; now in the final verse Jesus the risen Lord confirms the promise, ‘I am with you always.’
Each of their essential points combine for an overarching consequence for the believer: universal kingship and accompaniment until the end of the age, means that there is a universal and timeless element to mission.
The closing words of the Mass in Latin: ite, missa est. Ite is the imperative/command tense of the word go. In other words, it is not a suggestion. The expression missa est is often translated from classical Latin, but the expression really evolves from Late Latin where missa was what would be is classical Latin, missio. While both terms mean “dismissal”, in evolving Christian reflection, the understanding of the command focused on the purpose of the dismissal: mission.
The connection between the meaning “dismissal” and the ‘deeper’ meaning of “mission” was also discussed by Benedict XVI in Sacramentum caritatis (2007): “In antiquity, missa simply meant ‘dismissal’. In Christian usage, however, it gradually took on a deeper meaning. The word ‘dismissal’ has come to imply a ‘mission’. These few words succinctly express the missionary nature of the Church”
The simple command Jesus gave to his disciples: “Go!” The same command He gives us at the end of Mass: “Go!” Like the apostles, we are a people sent into the world to proclaim the Good News.