As David Pao has pointed out, Luke brings a particular Old Testament text into great prominence by placing it at the beginning and end of each of his two books, Luke and Acts, and by referencing it at several other times. The text is Isaiah 49.6, one of the ‘servant songs’ found in Isaiah 40-53 that has to do with God sending his servant to restore his people after their being exiled because of their sins:
Isaiah 49:6 It is too light a thing that you should be my servant to raise up the tribes of Jacob and to bring back the preserved of Israel; I will make you as a light for the nations, that my salvation may reach to the end of the earth."
The highlighted words should be noted as they are likely indications that this verse is in mind when they appear in various places in Luke and Acts. Note that ‘Gentiles’ and ‘nations’ are equivalent, and Isaiah 49.6’s idea of a salvation to Israel and then to the Gentiles/nations is something found in several texts in Luke and Acts and is really the basic message that Luke tells of the Church in Acts.
The passage first appears as part of Simeon the prophet’s witness to the baby, Jesus:
Luke 2:30-32 … for my eyes have seen your salvation 31 that you have prepared in the presence of all peoples, 32 a light for revelation to the Gentiles, and for glory to your people Israel."
At the end of Luke, Lk. 24.45-49, the risen Christ appears to his disciples in Jerusalem and commits them to the mission of Isaiah 49:6.
Luke 24:45-49 Then he opened their minds to understand the Scriptures, 46 and said to them, "Thus it is written, that the Christ should suffer and on the third day rise from the dead, 47 and that repentance and forgiveness of sins should be proclaimed in his name to all nations, beginning from Jerusalem. 48 You are witnesses of these things. 49 And behold, I am sending the promise of my Father upon you. But stay in the city until you are clothed with power from on high."
The same text of Isaiah is alluded to at the beginning and end of the book of Acts:
Acts 1:8 But you will receive power when the Holy Spirit has come upon you, and you will be my witnesses in Jerusalem and in all Judea and Samaria, and to the end of the earth."
Acts 28:28 Therefore let it be known to you that this salvation of God has been sent to the Gentiles; they will listen."
Within Acts are two further references to Isaiah 49.6 in reference to the mission being extended from Jews rejecting it to Gentiles accepting it. In Paul’s and Barnabas’s speech to Jews in Antioch we find the first of these:
Acts 13:46-47 And Paul and Barnabas spoke out boldly, saying, "It was necessary that the word of God be spoken first to you. Since you thrust it aside and judge yourselves unworthy of eternal life, behold, we are turning to the Gentiles. 47 For so the Lord has commanded us, saying, "' I have made you a light for the Gentiles, that you may bring salvation to the ends of the earth.'"
The language of ‘a light to the Gentiles’ not only appears in the servant passage of Isaiah 49 but also in the first servant passage of Isaiah 42:
Isaiah 42:6 "I am the LORD; I have called you in righteousness; I will take you by the hand and keep you; I will give you as a covenant for the people, a light for the nations….
As Pao says with reference to Acts 13.46-47’s use of Isaiah 49.6, the mission of Jesus, who was taken by the Church to be the ‘servant’ in Isaiah, is transferred to Paul and Barnabas. We might add that this mission is further transferred to the Church at large as it, too, fulfills Jesus’ mission. There are, to be sure, differences between what Jesus accomplishes through the cross and faith in him and what Paul and Barnabas and other apostles accomplish in their missionary witness to the nations of Jesus and what the Church at large does in its participation in this mission. But it is the same mission—a mission of the servant restoring the exiles and including the Gentiles to God’s reign.
The second reference within Acts comes in Paul’s speech to the Gentile governor of Israel, Festus, and King Agrippa:
Acts 26:22-23 To this day I have had the help that comes from God, and so I stand here testifying both to small and great, saying nothing but what the prophets and Moses said would come to pass: 23 that the Christ must suffer and that, by being the first to rise from the dead, he would proclaim light both to our people and to the Gentiles."
Several important points might be made in regard to Luke’s use of Isaiah 49:6.
1. Mission as a Fulfillment of Isaiah’s Prophecies of the Return from Exile: As with Matthew 28:16-20, Luke’s story of Jesus’ commission of his disciples for mission is a fulfillment of the promise in Isaiah of a mission to restore the exiles of Israel and include the Gentiles. While Matthew seems to allude to Isaiah 66.18-23, Luke alludes to Isaiah 49.6. Yet both texts have the story of Israel’s redemption or restoration from exile in view.
2. The Story of Mission: Both the story of Jesus and the story of the Church are missional and part of the same story of mission.
3. The Servant’s Mission: As Jesus fulfills the role of the servant of Isaiah, so, too, the apostles and the Church pick up this role in their mission to the ends of the earth. The disciples are witnesses to the salvation of Jesus sent out to the ends of the earth. The Church is the ‘city on a hill’ (Isaiah 2.1-5; cf. Micah 4) where the exiles return and Gentiles come to learn righteousness.
4. Salvation: Jesus accomplishes the salvation offered to both Israel exiled for her sins and the sinful Gentiles through his death on the cross. The mission is a mission that addresses the problem of sin in the world. Israel was exiled for her sins and the Gentiles were peoples living outside God’s covenant and therefore in their sins. One cannot interpret the Church’s mission in terms of ‘liberation’ apart from seeing this liberation in terms of being set free from one’s own sinfulness.
5. The Nations: Given the prophecies of Israel’s return from exile among the nations and some Gentiles joining them to learn righteousness, the mission of God is conceived not merely in terms of personal salvation but also in terms of the obedience of the nations to God. This theme brings in a dimension to missions of (a) going (b) cross-culturally (c) to make disciples. Yet this international and cross-cultural mission is more a matter of transforming people and cultures by teaching them God’s ways and teaching them to walk in his paths (Micha 4.2).
6. The Holy Spirit: The importance of the Holy Spirit to accomplish this mission is highlighted by Luke. Jesus accomplished his ministry in the power of the Holy Spirit (Luke 3.21-22; 4.1). Similarly, the Church is told to wait in its mission until it has received power from on high, the Holy Spirit.
 David W. Pao, Acts and the Isaianic New Exodus (Grand Rapids, MI: Baker Academic, 2002; originally published by J. C. B. Mohr (Paul Siebeck), 2000) as volume 130 in Wissenschaftliche Untersuchungen zum Neuen Testament Series 2.
 Note the term ‘consolation’ in regard to Simeon: Luke 2:25 says, ‘Now there was a man in Jerusalem, whose name was Simeon, and this man was righteous and devout, waiting for the consolation [paraklēsis] of Israel, and the Holy Spirit was upon him’. The related verbal form of the word, ‘to comfort’ (parakaleō), is used consistently in Isaiah for Israel’s salvation, as Pao (p. 46) says (see Is. 35.4; 40.1, 11; 49.10, 13; 51.3, 12; 57.18; 61.2; 66.10-13). Note that two texts in this list are from Isaiah 49 in reference to God’s servant. The theme of Israel’s ‘comfort’ or restoration from captivity is established at the beginning of the section of Isaiah devoted to Israel’s restoration from captivity—Isaiah 40-66—as Is. 40.1 says, ‘Comfort, comfort my people, says your God.’ Israel’s ‘salvation’ is her ‘consolation’ in captivity—her restoration from exile.
 The ‘pouring out’ on ‘us’ of the ‘Spirit from on high’ is, in Isaiah 32.15, stated in reference to the time when a righteous king who would establish Israel after her destruction. God’s giving of the Spirit occurs with the comfort/consolation of Israel, the return from exile. Thus, while the disciples hoped for a restoration of Israel more literally (Acts 1.6), the promises of the restoration of Israel from exile were being fulfilled in the mission of the Church.
 Pao, p. 100.
 Here I am pushing back against a century of literature about the enculturation of the Gospel. There is some truth in this: the Gospel can be ‘translated’ into other cultures and languages. That is a highly significant point. However, the force of this argument in missional literature and theology has all too often undermined the more significant point in the Scriptures that peoples are included into God’s people, cultures are transformed by the Gospel, and people learn to walk in God’s ways. If colonial theologies are to be criticized as encasing the Gospel in Western theology, post-colonial theologies have not fared any better. They have not liberated the Gospel from culture but simply replaced Western culture with other cultures. The Scriptures perceive all cultures—Israel’s and the cultures of the Gentiles—as forces that can and often do undermine the ‘ways of the Lord’. There is no absolute celebration of culture; rather, God’s mission intends to transform cultures where they run contrary to God’s ways.