Surely these men did not deliberately intend to sin. However, notice how quickly God's sense of justice reacted, striking these men dead in their tracks and burning them to cinders. Obviously, they either did or failed to do something far more serious than ever entered their minds. Is not God's reaction a vivid warning, especially to those who come near Him? Are we not among those who come near Him?
Look at the evidence more closely and observe God's sense of justice. First, these men were the sons of Aaron, and Moses was their uncle. One would think that, if anybody among those two to three million Israelites had a close relationship with God, that family did. So one might think there may have been some leeway in God's judgment, but there was not! God reacted swiftly and violently.
Second, the charge against them was not because they consorted with prostitutes. No human sacrifices were planned or made. The charge was that they used "profane" (NKJV) or "strange" (KJV) fire.
But we need to look further. Just a few days before this startling event, Exodus 40 reveals the construction of the Tabernacle had been completed and its furniture arranged. Leviticus 1 begins listing the final procedures made for God to dwell in the Tabernacle. In Leviticus 8, the priesthood was consecrated, and in Leviticus 9, they made their first official offering using the Tabernacle and its furniture. Leviticus 9:22-24 says:
Then Aaron lifted his hand toward the people, blessed them, and came down from offering the sin offering, the burnt offering, and peace offerings. And Moses and Aaron went into the tabernacle of meeting, and came out and blessed the people. Then the glory of the LORD appeared to all the people, and fire came out from before the LORD and consumed the burnt offering and the fat on the altar. When all the people saw it, they shouted and fell on their faces.
This spectacular and serious event shows the offering's acceptance by God.
To this point, all was well, but we must consider a solemn command given by God to the Levites regarding their responsibilities in Leviticus 6:12-13:
And the fire on the altar shall be kept burning on it; it shall not be put out. And the priest shall burn wood on it every morning, and lay the burnt offering in order on it; and he shall burn on it the fat of the peace offerings. A perpetual fire shall burn on the altar; it shall never go out.
The altar fire was to be rekindled continually from its own coals, which remained from God's acceptance of the original offering. What was Nadab and Abihu's sin? They used coals from a fire not ignited by God. It was not from His hand and therefore was foreign fire.
If we read between the lines here, we can easily see that Aaron was shocked. He went right to the top of human leadership to get this straightened out, and Moses gave him God's answer: Do not mourn. Do not show any agreement with Nadab and Abihu. Do not show any disagreement with God's judgment.
Why? God's judgments are never wrong. Nadab and Abihu got what they deserved. God saw every aspect of their act as it unfolded. They had added or subtracted to what God commanded and died. They had tried to get by with what they carnally felt was acceptable.
The instruction is clear: Among those consecrated by God to serve Him and His family, His instructions must be explicitly followed. They totally disregarded what He had commanded in Leviticus 6:12-13. There is no ambiguity in the instructions. They had been completely and adequately informed. Each step and each instrument in the process had been designed to teach certain spiritual concepts. They had thought that common fire was good enough, but in their careless, presumptuous neglect, they had blatantly twisted God's Word.
This incident vividly illustrates that the wages of sin is death. Leviticus 10:3 says Aaron held his peace; he knew the judgment was correct. It was a shocking demonstration, but we can be certain that, because God is love and is supremely sovereign in His judgment, His every decision will be as correct as His judgment of Nadab and Abihu, since He Himself is the standard.
God is not a holy terror lying in wait for us to do something wrong, but He provides us examples such as this and several others of what He can do in response to sin. When He responds like this, He is fully justified. He wants us to consider His justice so that we will be better prepared to evaluate our calling properly and then live by faith.