The ties between the reading from Jeremiah and the Gospel run deep. In order to see these ties we might want to understand Christ's words, "There is a baptism with which I must be baptized." The Catechism of Catholic Church (CCC) tells us in paragraph 1214 "to baptize (Greek baptizein) means to "plunge" or "immerse..." In our Christian understanding of our Sacrament, "the 'plunge' into the water symbolizes the catechumen's burial into Christ's death, from which he rises up by resurrection with him.."
When Christ says, "there is a baptism..." he is foretelling his own death. Denis the Carthusian explains this statement in Christ's own words saying, "there remains for me the duty of receiving a baptism of blood, that is, of being bathed, soaked upon the cross not in water but in my own blood poured out to redeem the whole world." Christ's baptism, the baptism that he offers us, is entrance into his passover, which does not begin on the Cross and does not end on the Cross.
Christ's passover is not a passover into death but into life. Christ was bathed in his own blood, and plunged into the tomb and plunged into the abode of the dead. But his "plunge" was not simply a plunge but also a rising from that plunge. That is to say that Christ's burial is meaningless without his resurrection. "If Christ has not been raised, our preaching is in vain and your faith is in vain" (1 Cor 15:14).
Now, hearken back to Jeremiah's arrest. And his "plunge" into the muck of the cistern. The early Church would have seen this clearly as a foreshadowing of Christ's passion. The Navarre commentary states:
One ecclesiastical writer, Olympiodorus, interpreted Jeremiah’s imprisonment as a prefigurement of Jesus’ passion and death. Commenting on v. 6, he said: “The prophet becomes a figure of the mystery of Christ, who was handed over by Pilate to the Jews, descended into hell, and was raised from the dead. Jeremiah climbs out of the cistern he was cast into; Scripture often refers to hell as a cistern” (Fragmenta in Jeremiam, 38, 6).Note also, that "three" men come to lift Jeremiah from the cistern. Christ's resurrection is a divine act of the Trinity. In our baptism we are put to death, but raised up by the Trinity, as "a new creature" (cf. 2 Cor 5:17; Gal 6:15).
Now let us consider His words, "I have come to set the earth on fire, and how I wish it were already blazing!" Christ sets this fire by His baptism, by the same baptism that we are baptized into. St. John Chrysostom comments on Christ's words saying:
For by the earth He now means not that which we tread under our feet, but that which was fashioned by His hands, namely, man, upon whom the Lord pours out fire for the consuming of sins, and the renewing of souls.In Latin, we see the relation between human—homo—and the earth—humo—a little more clearly, which is very much the same in Hebrew, the original language of the story of Genesis, which is where this whole story begins.
Now, consider briefly the word "fire." Fire burns, destroys, it purifies gold and burns up impurities. It produces warmth and light. It consumes the sacrificial offering and sends up the smoke of incense and prayer. All the more the Holy Spirit, then, sets man ablaze with love, a love that purifies the heart, produces warmth, enlightens the mind, and consumes the offering of our life producing of it a prayer that rises up to God.
So, what's the point of all this? Why does this lead to division?
1 Peter 4:12-19 answers this for us:
Beloved, do not be surprised at the fiery trial when it comes upon you to test you, as though something strange were happening to you. But rejoice insofar as you share Christ's sufferings, that you may also rejoice and be glad when his glory is revealed. If you are insulted for the name of Christ, you are blessed, because the Spirit of glory and of God rests upon you. But let none of you suffer as a murderer or a thief or an evildoer or as a meddler. Yet if anyone suffers as a Christian, let him not be ashamed, but let him glorify God in that name.Setting the world on fire is about the Spirit. It is about sharing this Spirit, by taking it into ourselves. Ultimately, it is about Baptism. It is about Christ's baptism and our union with Christ by our baptism, a union of love effected by the Holy Spirit. It is a call to live out our baptismal promises and the life—that is the fire—we received at baptism.