Like a painting placed inside a beautiful frame, John the Baptist's ministry (3:2b-3) is bracketed between the historical context (3:1-2a) and the context of Old Testament hope (3:4-6). Among the Gospel writers, only Luke takes the time to mention leaders in power at various political levels when John appeared. Luke is also unique in emphasizing the extent to which John's coming represents a renewed realization of the promise of Isaiah 40:3-5. For Isaiah, the initial fulfillment of seeing God's hand had been in the deliverance from exile during the period of Cyrus the Great, as later chapters of Isaiah note. Now the pattern of God's working to deliver his people is renewed in the word of a voice of one calling in the desert. God approaches, and creation is to level all geographical obstacles to prepare for his coming, as if rolling out a great red carpet. This leveling includes seeking contriteness of heart (Is 57:14-17).
In listing Tiberius Caesar, Pontius Pilate, Herod, Philip, Lysanias, Annas and Caiaphas, Luke surveys the political and religious leadership from the most distant to the more directly involved authorities. The note about Tiberius's fifteenth year allows us to date the start of John's ministry. Assuming the calendar being used is a Roman one, John's ministry began somewhere during A.D. 28-29. The dating of this starting point is related to the dating of Jesus' ministry, which probably ended in A.D. 33 (though many date the end of his ministry in A.D. 30). Annas and Caiaphas are both called high priests, although only one high priest existed at a time. This description appears to be a case of a person of high office keeping his title even after leaving office, much like an ex-president or ex-governor today. Pilate and Herod reappear only briefly in 9:7-9 and 23:1-25, but both rulers are much discussed in ancient Jewish sources. Philip and Lysanias were the other regional tetrarchs of the period. They, like Herod, were descendants of Herod the Great, who ruled the entire area when Jesus was born.
John's ministry begins during this period. He ministers in the wilderness, brings the word of God and preaches a baptism of repentance for the forgiveness of sins. The concept of repentance is central to Luke. Not only is its concrete character elaborated in 3:10-14, but Jesus, in his Great Commission in 24:43-47, makes it clear that the roots of the concept come from the Old Testament. Though the Greek term for repentance means "a change of mind," the Semitic concept involves a "turning," an attitude that brings a change of direction (1 Kings 8:47; 13:33; Ps 78:34; Is 6:10; Ezek 3:19; Amos 4:6). Other texts in Luke emphasize this term (5:32; 10:13; 11:32; 13:3, 5; 15:7, 10). On this point Jesus and John echo one another. It is a contrite heart that comes to God for forgiveness, one who knows the need of a spiritual physician (5:31-32). A walk with God means submission to him and a change of direction.
John's baptism is a one-time rite in preparation of God's approaching salvation. Its roots may well go back to the Old Testament association of the Spirit's presence and washing (Ezek 36:25-27). Though John makes clear that Jesus is the one who brings the Spirit (Lk 3:15-17), John's baptism pictures a preparation for what God will do in Jesus.
Still, John's baptism differs from Christian baptism. John's baptism looks forward, while Christian baptism assumes Jesus' provision of the Spirit. John's baptism anticipates the Spirit's coming, while Christian baptism reflects the Spirit's arrival through Jesus. The washing aspect of John's baptism allows it to be associated with forgiveness of sins, as its connection to the Ezekiel 36 imagery suggests. Here are people of contrite heart, looking to God expectantly for what he will do in the days to come. Acts 19:1-10 reinforces the picture that John's baptism is anticipatory and not an end in itself: when some disciples appear in Ephesus who only knew John's baptism, they are led by Paul to experience what John's washing anticipated—the experience of being indwelt by the Holy Spirit (Lk 3:15-17; Acts 10:37-38; 13:23-24). When an Israelite takes John's baptism, he or she is declaring openness to God and his ways. The nation is put on notice to await the rest of God's promise.
This message is why Luke cites Isaiah 40:3-5, with its promise of the coming of God's salvation. As already noted, this Isaiah text is a "pattern" prophecy, speaking to many periods of history at the same time. In Isaiah these verses introduce the entire second section of the book, which overviews God's saving program for Israel, starting with deliverance from exile and ending in the utopian existence described in Isaiah 65—66. Thus a range of events is in view.
Luke shows how the pattern begins yet again with John the Baptist in the wilderness. John is like Elijah, as Mark 1:2-3 and Luke 1:16-17 note (Mal 3:1). The passage itself compares preparing for the events of salvation to preparing a red-carpet reception for a king. The creation is called to level the path so God can enter. With his entry God makes salvation manifest for all to see. There is nowhere else to look for God's saving work except to Jesus. The appeal to the leveling of creation is best seen as including the removing of moral obstacles to God's arrival. John is the sentry who issues the moral call to clear the way for his coming. The other Gospels make it clear that John also announces that the kingdom of God has "come near," something Jesus also declares (Mt 3:2; Mk 1:14-15). This announcement indicates that some aspect of God's rule approaches that had not been present previously. For the promised kingdom to be "near" means that it is not yet present when John speaks. So John is not speaking of the kingdom of God in its broadest sense of God's rule from the beginning of the creation. Rather, he is discussing the promised, long-awaited rule of God in which the promised Messiah and God's Spirit become evident in a fresh and startling way. John is saying that finally God is fulfilling the long-awaited hope of Old Testament promise.
John's later remarks about the Spirit (3:15-17; Mt 3:11-12) make it clear that one of the signs of the kingdom's arrival will be the Messiah's distribution of the Spirit, an event Peter declares as initially fulfilled in Acts 2:30-36 and in which all believers today share. When the Spirit comes, Messiah is at work, kingdom blessings begin to be realized, and Old Testament promise is coming to pass (Rom 16:25-27; Heb 1:1-13).