3:15–16 John’s preaching raises eschatological expectations, and people begin to wonder if he is the Messiah. The verb rendered “expectation” here (Gk. prosdokaō) appears in Luke 7:19–20, where John sends messengers to ask Jesus if he is the Messiah they are anticipating. The people of Israel are reflecting on and pondering whether John fulfills the messianic role, since he calls upon people to repent as the day of the Lord approaches. His baptism also suggests that he plays a unique role in the unfolding of God’s purposes.

John rejects any notion that he is the Messiah, and his refusal to accredit himself as the Christ is also clear in the Gospel of John. John “was not the light, but came to bear witness about the light” (John 1:8). He specifically disavows the notion that he is the Christ (John 1:19–20; 3:28), emphasizing that Jesus takes precedence over him (John 1:15; 3:29–30). Here John describes his lesser role in a distinctive manner as he reflects on his baptism. There is significant discussion regarding the origin of John’s baptism. Some have argued that it came from Qumran, but John’s baptism is a one-time event whereas Qumran witnessed repeated lustrations. Others think John’s conception of baptism derives from proselyte baptism, but the sources for proselyte baptism are later, and thus it is difficult to know if John picks up the idea from fellow Jews or they pick it up from him. In any case, baptism, the washing of the body in water, is a fitting picture of the cleansing needed for a nation that has gone astray.

John declares to the people that a stronger one is coming, and that the coming one is so much greater that John is not even worthy to untie his sandals. Even slaves were not required to untie the thongs of their masters.41 The coming one, the stronger one, would baptize not with water but with the Holy Spirit (cf. Matt. 3:11; Mark 1:7–8; Acts 1:5). As Acts 10:38 says, Jesus was “anointed . . . with the Holy Spirit and with power.” John draws here on the promises of the coming of the Holy Spirit in the OT prophets. When the Spirit comes, the new creation will dawn (Isa. 32:15). The Lord promises to pour out his Spirit on his people (Isa. 44:3), and in Isaiah 40–66 the gift of the Spirit is tied to return from exile. The Lord says he will cleanse his people with water, give them new hearts, and put his Spirit within them so they will walk in his ways (Ezek. 36:25–27). When the Spirit comes, Israel will be restored from exile and live in the land again (Ezek. 37:14). Joel anticipates the day in which the Spirit will be poured out on all (Joel 2:28–29). The Messiah who comes after John—Jesus—will be the one who baptizes his people in the Spirit, signifying that the day of restoration has arrived.

Baptism with fire could refer to judgment, since fire often denotes judgment in the OT (e.g., Isa. 66:15–16; Jer. 23:29; Nah. 1:6; Zeph. 1:18; 3:8). If this is the case, then Luke 3:17 continues the theme of judgment from verse 16. It is more likely, however, that Isaiah 4:2–5 is the background, where the prophet speaks of the remnant preserved in Jerusalem. The filth of the people will be “cleansed . . . by a spirit of judgment and by a spirit of burning” (Isa. 4:4). Then the Lord’s presence will be restored in Israel, the same way he dwelt with the people during the exodus (Isa. 4:5). If this is the case, then the Spirit as fire refines and purifies the people of God (cf. Zech. 13:9; Mal. 3:2).

3:17–18 The picture here is of both wheat and chaff on the threshing floor. A rake or shovel is brought in to clear the floor, removing the chaff, while the wheat is deposited in the barn. The OT compares the wicked to chaff, which is easily blown away (Pss. 1:4; 35:5; 83:13; Isa. 17:13; Hos. 13:3; Zeph. 2:2). The wheat, of course, stands for the righteous, who will escape judgment. The Messiah will immerse with the Spirit those who belong to him, but those who are judged will be burned “with unquenchable fire” (cf. Mark 9:43). Unquenchable fire refers to everlasting judgment, since it does not make much sense for the fire to continue forever if there is nothing to burn. Luke completes and summarizes John’s message by stating how he urges them (Gk. parakalōn) to repentance and proclaims the good news (euēngelizeto). John heralds the coming kingdom and tells people they must turn to the Lord to escape judgment.

3:19–20 Herod Antipas (r. 4 BC–AD 39) is the ruler named here, with Luke picking up the reference to him from 3:1. Herod Philip (r. 4 BC–AD 34), also mentioned in verse 1, is also in view, though he is not named here. Philip was married to Herodias, but she divorced Philip and married Herod Antipas.42 John rebukes Herod for taking the wife of his brother (cf. Matt. 14:4; Mark 6:18). Herod does not respond to John’s reproof in a fitting way but exacerbates his evil by imprisoning John. It is evident that Herod is guilty of many other sins, which Luke passes over here. In any case, John’s imprisonment removes him from the scene, signaling that his public ministry has ended. He has accomplished what he was intended to do, for the public ministry of Jesus is about to begin. The overlap between the ministries of John the Baptist and Jesus is omitted by Luke (cf. John 1:19–51) since he concentrates on the big picture: Jesus’ succeeds John and is superior to him.