12:49 The need for faithfulness and obedience as disciples (12:35–48) is followed by the purpose of Jesus’ mission. In saying that he has come to cast fire on the earth that he wishes were kindled now, Jesus certainly refers to judgment. In the OT fire often designates judgment. For instance, Jeremiah’s words are as fire that consumes the people (Jer. 5:14; 23:29; cf. Sir. 48:1). Amos warns Israel to seek the Lord, lest he “break out like fire” (Amos 5:6). On the other hand, in Luke fire also refers to the transforming work of the Spirit (Acts 2:3), and in Isaiah 4:4 the Spirit as fire both cleanses and purifies. Thus both ideas are likely present here. Jesus, as in the next verse, anticipates his death and resurrection, the consummation of his work. The final day of judgment will not come immediately, but judgment and salvation are inaugurated when Jesus’ work on earth is completed.

12:50 The reference to baptism looks forward to the cross, to the great saving and judging event of Jesus’ ministry. In this context the image probably looks back to the flood narrative in Genesis 6–9, in which the world is judged for its evil. Jesus’ baptism refers here to his death, when he is submerged, so to speak, under the waters of God’s wrath when judgment sweeps over him. We have seen that his journey toward Jerusalem anticipates this day of judgment. Jesus is distressed since he will experience God’s wrath for the sake of his people. His baptism will fulfill God’s plan of salvation (cf. Luke 18:31), and thus Jesus’ entire ministry hinges on this great event.

12:51–53 The coming fire and baptism will affect not only Jesus but all humanity. He came to bring peace, but peace is not the only consequence of his coming. Both peace and division, harmony and conflict, joy and strife will occur because of his fire and baptism. There will be only peace with those who have received his favor (2:14). Some will oppose and stand against the Messiah (2:34). Most Jews probably thought that when the Messiah came, he would be welcomed with open arms, but the reality is more complex and nuanced. Houses will be deeply divided, and the kingdom will not come in its fullness immediately. A period of sifting and testing will come first, in which people will go different ways. These divisions will even enter into families; universal family harmony will not be possible, for fathers will disagree with sons, daughters with mothers, and daughters-in-law with mothers-in-law. Jesus picks up here the words of Micah 7:6, from a chapter in which Micah looks forward to the day in which Israel will be delivered. Still, Micah suggests that enemies will continue to afflict God’s people. The deliverance will not be immediate or instantaneous.