In the famous episode of Elijah and the priests of Baal, it should be noted how dedicated the priests of Baal were. They built an altar, and danced around it for half of the day. When there was no fire from heaven, their dedication became more frenzied, and they began to leap on the altar (1 Kings 18:26). Elijah then began to mock them, and they doubled down — that was the point where they began to cut themselves until the blood gushed out (1 Kings 18:28). They had everything — a religion, dedication, an altar, devout activity, enthusiasm, and their own blood on the altar. They had everything except for a god.
Elijah prepared his altar meticulously, and had a trench dug around it, and had water poured over it three times. Both altars had a bullock, but their altar had human blood, their own, while Elijah’s had an abundance of water.
It is tempting to say that the great miracle was how God answered with fire from the sky (1 Kings 18:38), or a bit later that day with water from the sky (1 Kings 18:45), but this would be to miss the point of the sign. The miracle of the fire from heaven was a sign of God’s ability to do something else, something greater.
“Hear me, O Lord, hear me, that this people may know that thou art the Lord God, and that thou hast turned their heart back again” (1 Kings 18:37).
God answered with fire so that the people would know two things — first that the Lord was God, and secondly, so that they might know that God had indeed turned their hearts back to Him again.
A similar sign was given again, centuries later, when the fires of Pentecost came down upon the heads of the disciples. And centuries later, it still meant the same thing — the Lord is God, and we must be born again.
Elijah sure used a lot of water when just a sprinkle would have done well enough to make his point.