We know very little about these two men and their character, or even about what they were thinking and reasoning when they committed this sin of offering "unauthorised fire." We only know that they were sons of Aaron and were part of the top tier of leadership under Moses. (See Exodus 24: 9) As priests, they had heard and practised Levitical law and they knew that the stakes were high. (See Leviticus 8: 35) Their job came with privileges, but also with sacrifices and with risky responsibilities.
Were they being deliberately rebellious in this incident, or were they simply negligent and presumptuous, not taking seriously the holiness of God and the gravity of disobedience? The outcome seems harsh (the two men died) but this was the beginning of the Israelites' history as a nation and precedents were being set. The ultimate role of the priesthood was to reflect God's holiness to the people, so that they wouldn't embrace the abhorrent practices of the people around them - practices like child sacrifice and bestiality. It was absolutely critical that the people learned the importance of uncompromising obedience to God's instructions.
This is equally crucial for us in the 21st century. We live in a generation where doing your own thing, doing what feels or seems right in your own eyes, is a high value, strongly defended by our society. As Christians, we need to be careful that we are truly living our lives by God's standards and not according to our own opinion, to the trends of the world around us, or to the traditions of a bygone age. If we compromise (see next post below) or take God's instructions lightly, we will never be able to reflect His love and holiness to a world that is desperately in need of Him.
The dramatic demise of Nadab and Abihu possibly shocked the whole nation; the people were learning the importance of uncompromising obedience and the cost of indifferent negligence or wilful disobedience. There's a tense moment later in the chapter when another two men completely burn up an animal instead of eating it. This too was their own idea, and not what the priests had been commanded to do. Their action is later forgiven when they explain that they intended it to be an act of contrition for the sin of the first two men. However, the general principle is clear: our to-the-letter obedience is more important than our apparently noble acts of self-sacrificing religious activity.
As the prophet Samuel expressed it many centuries later: What is more important to the Lord; your burnt offerings and sacrifices or your obedience to His voice? To obey is better than sacrifice, and heeding God's will is better than offering up the fat of rams. (1 Samuel 15: 22)
No amount of religious activity can ever be a substitute for hearing and obeying the voice of God, and these early Israelites were seeing this principle in action, way back in the days of Leviticus.
