And he put the wood in order ... - He obeyed, that is, all the injunctions of the Law with respect to the offering of a burned sacrifice (marginal reference). He thus publicly taught that the ordinances of the Law were binding upon the kingdom of Israel.

Barrels - Rather, "pitchers" or "water-jars," such as the maidens used to carry on their heads (Genesis 24:14-20. Compare Judges 7:16, Judges 7:19). The flooding the sacrifice and the trench with water would at once do away with any suspicion of fraud, and greatly enhance in the eyes of the people the marvelousness of the miracle. The unfailing spring at the eastern end of Carmel 1 Kings 18:19, was capable of furnishing as much water as he needed.

Fill four barrels - This was done to prevent any kind of suspicion that there was fire concealed under the altar. An ancient writer under the name of Chrysostom, quoted by Calmet, says that he had seen under the altars of the heathens, holes dug in the earth with funnels proceeding from them, and communicating with openings on the tops of the altars. In the former the priests concealed fire, which, communicating through the funnels with the holes, set fire to the wood and consumed the sacrifice; and thus the simple people were led to believe that the sacrifice was consumed by a miraculous fire. Elijah showed that no such knavery could be practiced in the present case. Had there been a concealed fire under the altar, as in the case mentioned above, the water that was thrown on the altar must have extinguished it most effectually. This very precaution has for ever put this miracle beyond the reach of suspicion.

And he put the wood in order, and cut the bullock in pieces, and laid him on the wood,.... Just in such manner as sacrifices usually were:

and said, fill four barrels with water; either from the brook Kishon, or, if that was dried up, from the sea; for both were near this mountain, and so to be had, though a time of drought:

and pour it on the burnt sacrifice; that which was intended to be one:

and upon the wood: wherewith it was to be burnt, and so made unfit for it; and which would make the miracle appear the greater, when fire came down and consumed it.

And he put the wood in order, and cut the bullock in pieces, and laid him on the wood, and said, Fill four barrels with water, and pour it on the burnt sacrifice, and on the wood.

18:33 With water - This they could quickly fetch, either from the river Kishon; or, if that was dried up, from the sea; both were at the foot of the mountain. This he did to make the miracle more glorious, and more unquestionable.

18:21-40 Many of the people wavered in their judgment, and varied in their practice. Elijah called upon them to determine whether Jehovah or Baal was the self-existent, supreme God, the Creator, Governor, and Judge of the world, and to follow him alone. It is dangerous to halt between the service of God and the service of sin, the dominion of Christ and the dominion of our lusts. If Jesus be the only Saviour, let us cleave to him alone for every thing; if the Bible be the world of God, let us reverence and receive the whole of it, and submit our understanding to the Divine teaching it contains. Elijah proposed to bring the matter to a trial. Baal had all the outward advantages, but the event encourages all God's witnesses and advocates never to fear the face of man. The God that answers by fire, let him be God: the atonement was to be made by sacrifice, before the judgment could be removed in mercy. The God therefore that has power to pardon sin, and to signify it by consuming the sin-offering, must needs be the God that can relieve from the calamity. God never required his worshippers to honour him in the manner of the worshippers of Baal; but the service of the devil, though sometimes it pleases and pampers the body, yet, in other things, really is cruel to it, as in envy and drunkenness. God requires that we mortify our lusts and corruptions; but bodily penances and severities are no pleasure to him. Who has required these things at your hands? A few words uttered in assured faith, and with fervent affection for the glory of God, and love to the souls of men, or thirstings after the Lord's image and his favour, form the effectual, fervent prayer of the righteous man, which availeth much. Elijah sought not his own glory, but that of God, for the good of the people. The people are all agreed, convinced, and satisfied; Jehovah, he is the God. Some, we hope, had their hearts turned, but most of them were convinced only, not converted. Blessed are they that have not seen what these saw, yet have believed, and have been wrought upon by it, more than they that saw it.