Luke 12:49

And we must here believe that Christ came down from heaven. For if He had come from earth to earth, He would not say, I came to send fire upon the earth.

To stewards, that is, to Priests, the preceding words seem to have been addressed, that they may thereby know that hereafter a heavier punishment awaits them, if, intent upon the world's pleasures, they have neglected the charge of their Lord's household, and the people entrusted to their care. But as it profiteth little to be recalled from error by the fear of punishment, and far greater is the privilege of charity and love, our Lord therefore kindles in men the desire of acquiring the divine nature, saying, I came to send fire on earth, not indeed that He is the Consumer of good men, but the Author of good will, who purifies the golden vessels of the Lord's house, but burns up the straw and stubble. But so great was our Lord's condescension, that He tells us He has a desire of inspiring us with devotion, of accomplishing perfection in us, and of hastening His passion for us; as it follows, And how am I straitened till it be accomplished?

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.

Now it is the way of holy Scripture to use sometimes the term fire, of holy and divine words. For as they who know how to purify gold and silver, destroy the dross by fire, so the Saviour by the teaching of the Gospel in the power of the Spirit cleanses the minds of those who believe in Him. This then is that wholesome and useful fire by which the inhabitants of earth, in a manner cold and dead through sin, revive to a life of piety.

(in Ezech. lib. i. Hom. 2.) Or else, fire is sent upon the earth, when by the fiery breath of the Holy Spirit, the earthly mind has all its carnal desires burnt up, but inflamed with spiritual love, bewails the evil it has done; and so the earth is burnt, when the conscience accusing itself, the heart of the sinner is consumed in the sorrow of repentance.