What was their sin in thus offering it? Plainly, the narrative points to the essence of the crime in calling it 'fire which He had not commanded.' So this was their crime, that they were tampering with the appointed order which but a week before they had been consecrated to conserve and administer; that they were thus thrusting in self-will and personal caprice, as of equal authority with the divine commandment; that they were arrogating the right to cut and carve God's appointments, as the whim or excitement of the moment dictated; and that they were doing their best to obliterate the distinction on the preservation of which religion, morality, and the national existence depended; namely, the distinction between holy and common, clean and unclean. To plough that distinction deep into the national consciousness was no small part of the purpose of the law; and here were two of its appointed witnesses disregarding it, and flying in its face. The flash of holy fire consuming the sacrifices had scarcely faded off their eyeballs when they thus sinned.
They have had many successors, not only in Israel, while a ritual demanding punctilious conformity lasted, but in Christendom since. Alas! our censers are often flaming with 'strange fire.' How much so-called Christian worship glows with self-will or with partisan zeal! When we seek to worship God for what we can get, when we rush into His presence with hot, eager desires which we have not subordinated to His will, we are burning 'strange fire which He has not commanded.' The only fire which should kindle the incense in our censers, and send it up to heaven in fragrant wreaths, is fire caught from the altar of sacrifice. God must kindle the flame in our hearts if we are to render these else cold hearts to Him.
'The prayers I bring will then be sweet indeed If Thou the Spirit give, by which I pray.'
The swift, terrible punishment does indeed bear marks of the severity of that earlier stage of revelation. But it was not disproportioned to the offence, and it was not the cruelty of a martinet who avenged ceremonial lapses with penalties which should have been kept for moral offences. The surface of the sin was ceremonial impropriety: the heart of it was flouting Jehovah and His law. It was better that two men should die, and the whole nation perish not, as it would have done if their example had been followed. It is mercy to trample out the first sparks beside a powder-barrel.
There is a very striking parallel between verse 2 and the last verse of the preceding chapter. In both the same expression is used, 'There came forth fire from before the Lord, and consumed' (the word rendered _devoured_ in verse 2 is the same in Hebrew as _consumed_). So, then, the same divine fire, which had graciously signified God's acceptance of the appointed sacrifice, now flashed out with lightning-like power of destruction, and killed the two rebel priests. There is dormant potency of destruction in the God who reveals Himself as gracious. The 'wrath of the Lamb' is as real as His gentleness. The Gospel is 'the savour of life unto life' and 'of death unto death.'
Moses' word to the stunned father is of a piece with the severity of the whole incident. No voice of condolence or sympathy comes from him. The brother is swallowed up in the lawgiver. He puts into words the meaning of the terrible stroke, and expects Aaron to acquiesce, though his heart bleeds. What was his interpretation? He saw in it God's purpose to be 'sanctified in them that come nigh Him.' The priests were these. Nadab and Abihu had been consecrated for the purpose of enforcing the truth of God's holiness. They had done the very opposite, by breaking down the distinction between sacred and common.
But their nearness to God brought with it not only corresponding obligations, but corresponding criminality and penalty, if these obligations were not discharged. If God is not 'sanctified' _by_ His servants, He will sanctify Himself _on_ them. If His people do not set forth His infinite separation from all evil and elevation above all creatures, He will proclaim these truths in lightning that kills and thunder that roars. It is a universal law which Moses sternly spoke to Aaron instead of comfort, bidding him recognise the necessity of the fearful blow to his paternal heart. 'You only have I known of all the families of the earth, therefore I will punish you for all your iniquities.'