The Holy Spirit is a dominant theme throughout the book of Luke. The Holy Spirit fills individuals in Luke (John, Elizabeth, Mary, Jesus, Zechariah, Simeon, cf. 1:15, 1:35, 1:41, 1:67, 2:25, 3:22, etc), and the work of the Spirit is spoken of in contrast to the many “evil spirits” that cause damage to the individual (7:21, 8:2). The Spirit is associated in the births of both John and Jesus; John will be “filled with the Holy Spirit before birth” (1:15) and Jesus will be conceived through the power of the Holy Spirit (1:35). A common result from the infilling of the Holy Spirit is prophecy and praise (1:42-45, 1:64, 2:13). Joel Green and Scot Mcknight associate Luke’s use of the Spirit with prophetic acts that point to the recognition and assurance of salvation: “Elizabeth and Zechariah experience the Spirit of prophecy in invasive prophetic speech (the invasive quality denoted here by the Lukan favorite idiom “filled with” the Holy Spirit) … and as a result give oracles of recognition and assurance of salvation.”
The Holy Spirit appears in a very special way at Jesus’ water baptism (Lk 3:21-22; Mk 1:9-11; Mt 3:13-17; Jn 1:29-34).
It is interesting to note that in each of the Gospel accounts, Jesus’ baptism narrative introduces the rest of his ministry. What is really going on? What were the writers of the gospels telling their readers?
This moment is intentionally placed (in Luke’s account) in order to draw attention away from John the Baptism and centre in on Jesus. What Luke is saying to his readers, is that something special is going on here, a prophetic act in which the New Covenant is being announced. It’s like he’s saying “It’s time for the project of the New Creation to begin, and it begins here, with Jesus.”
Scholars don’t agree on the purpose of the dove ascending on Jesus, and what that may intend to mean. I believe that it’s meant to allude to 1) the Noah narrative, where the dove was a messenger of new beginnings (Gen. 8:8-12), and 2) the creation narrative, where God’s Spirit hovers over the waters right as he is about to bring forth creation ex nihilo (Gen. 1:2). The point, I think, is that God is now doing something NEW in Jesus. The project of New Creation is beginning in Jesus who is the Christ.
Jesus’ baptism in the Jordan is meant to signify this powerful new thing
that God is doing in history. It is “unique moment in history: the beginning of a new epoch in salvation-history – the beginning, albeit in a restricted sense, of the End-time, the messianic age, the new covenant.”
With regards to this narrative, NT Wright claims that “John the Baptist is playing Samuel to Jesus’ David,” and thus, Luke’s readers are given notice that “there is a new kingdom, a kingdom of Israel’s god, and that the young man now anointed by his cousin in the Jordan is the king through whom it is to be set up.”
The baptism of Jesus signifies the beginning of the in-breaking of the kingdom of God
, Jesus the Messiah, empowered by the Spirit, is bringing forth the year of the Lord’s favor: good news to the poor, liberty to the captives, the recovering of sight to the blind, and liberty those who are oppressed (Lk 4:18-19, cf Isa 61:1-2).
It is likely that Luke’s frequent mention of the Holy Spirit (much more than any other Gospel) is put to use in order to remind his readers that God “gives the Holy Spirit to those who ask him” (11:13), and may shed light on Luke’s intention to convey to the readers that now is the time of the new covenant, where God’s spirit is given to all flesh (C.F. Joel 2:28, Ez 33-36, Jer 36, Is 40-55).
The key here, is ALL flesh. This project is going to bring in the plan God had from the beginning, to make himself known to all the nations (cf Ez 36, Gen. 15, Jer 36). The allusion to Creation and the Noachic covenant points to God’s commitment to the whole of creation and serves to intensify the universal nature of God’s plan of salvation. It is likely that Luke intended the readers to recognize Jesus’ identification as the Messiah endowed with the Spirit in order to bring forth God’s eschatological program of salvation to all the nations.
It makes sense that Luke, throughout his gospel account, focuses on the outcasts of society; women, the poor, tax collectors, samaritans, etc. The point, I think, is that the Holy Spirit is offered to all (11:13), just as forgiveness is offered to all (3:3, 24:47). The gift of the Holy Spirit, it seems; will lead to Prayer, Praise, and Prophecy (yes, three P’s… my homiletics teacher would be proud). Through the Holy Spirit Jesus Promises Power (that’s got to be an A+)…and will eventually lead up to ….the day of Pentecost… (Okay I don’t know how this is happening right now)…
And finally it is on that day of Pentecost where the Spirit falls on all flesh. The New Covenant is materializing in a new and powerful way.
A little after Jesus’ baptism, he himself announces this New Thing that is happening, in him:
8 “The Spirit of the Lord is upon me,
because he has anointed me
to proclaim good news to the poor.
He has sent me to proclaim liberty to the captives
and recovering of sight to the blind,
to set at liberty those who are oppressed,
19 to proclaim the year of the Lord’s favor.”
 Dictionary of Jesus and the Gospels, ed. Joel B. Green and Scot Mcknight (Downers Grove, IL: InterVarsity Press, 1992), 342.
 James D.G. Dunn, Baptism in the Holy Spirit: A re-examination of the New Testament Teaching on the Gift of the Spirit in Relation to Pentecostalism Today (London: SCM Press, 1970), 24.
 N.T. Wright, The New Testament and the People of God (Minneapolis, MN: Fortress Press, 1992), 379.