1 And Nadab and Abihu, the sons of Aaron, took either of them his censer, and put fire therein, and put incense thereon, and offered strange fire before the Lord, which he commanded them not.
2 And there went out fire from the Lord, and devoured them, and they died before the Lord.
Nadab and Abihu offered up incense to the Lord by way of a “strange fire.” The Lord does not allow anything “strange” to approach Him. He had only one authorized ignition source in the entire tabernacle system: the fire on the altar of burnt offering. This fire had been lit by the Lord Himself on the inaugural day of the tabernacle. “Fire from heaven” is the biblical term. We call it a lightning. When I read “fire from heaven” I used to picture a heavenly flamethrower, like God was using a super-powered blow torch. But this was really more like a KAPOW! The lightning bolt came down and lit the wood under the offering. That’s fire from the sky; that’s fire from heaven. And the fire it ignited was never to go out. God started it and the priests were to maintain it. Every time they moved the camp, coals from that fire were to be kept and used to ignite the sacrificial flames once again. It had come from a pure and holy source, not from the efforts of man. It was from this fire that the lampstand was to be lit and from this fire that the altar of incense was to be fed.
Nadab and Abihu didn’t use these flames; they made their own. This is why it is called a strange fire. Their carelessness was made even more egregious by the fact that the heavenly fire had fallen just prior to their fatal offering. One can only assume what they must have been thinking. “Our father has a censer, we can have censers, too!” Or maybe it was, “Your fire, my fire, any ol’ fire will do!” Only the Lord knows. Whatever their motivation, their action was presumptuous. They decided to approach God in their own way at a time of their own choosing. As the people bowed with their faces to the ground in response to the Lord’s acceptance of the sacrifice, these men lit their censers with ordinary fire and endeavored to enter the holy of holies. Nothing fights fire like fire. With a blast, they were blown back out beyond the veil into the holy place.
Then Moses said unto Aaron, This is it that the Lord spake, saying, I will be sanctified in them that come nigh me, and before all the people I will be glorified. And Aaron held his peace.
This comment seems almost humorous in its blunt, I-told-you-so simplicity. Picture the scene in your mind. While the sacrifice is burning in response to the Lord’s acceptance, Nadab and Abihu saunter toward the tabernacle swinging their censors. Can you see Moses leaning over to Aaron and saying, “What are your boys doing?”
“I don’t know,” Aaron replies, “They’ve got incense. I suppose they are going in to worship.”
“Did you tell them to go in there?” Moses asks, now a bit concerned.
“No. You know my boys—they like taking the initiative,” Aaron says with a twinkle in his eyes, his shoulders rising with the comment.
“I don’t like this,” Moses hisses through clenched teeth, a small fist of fear balling up in his belly. Suddenly, an awful noise of roaring fire fills the air followed by the sound of clanging brass and two loud thuds. Through the open curtain of the door, Moses and Aaron can see two bodies smoldering outside the veil. “This is what I was talking about,” Moses says in a tight breath. “You can’t just walk in there any old time you please. This isn’t some false idol of stone we’re dealing with here. That’s the holy God YHWH in there and He’s dangerous. You’ve got to treat Him with fear and reverence, because He’s holy. Don’t you ever just go walking in there simply because you want to or we’ll have to drag you out!” And with this, he commands a couple of Kohathites to drag the bodies outside of the camp.
Aaron stands shock still, white-faced and tight-lipped. Moses doesn’t take a breath. He continues to give direction and commands. “You and your younger boys can’t fall apart here. Let your kinfolk mourn. But you are a priest before you are a father. YHWH demands more of your heart than you gave to your boys. Stand your post and keep your vestments on or His wrath will break out against the people.” These words soak into Aaron’s ears as his sons are dragged out of the sanctuary. He looks into the holy place, its gold furnishings gleaming in the glow of the lampstand. The veil flutters gently, animating the embroidered cherubim. He knows what lies beyond. He watched as the craftsmen built it. But the Ark had ceased to be a fancy chest to house the tablets. Its presence beyond the veil meant that the Lord Was There. And it was his job to approach that veil. It was his job to serve in the holy place, the very place his sons had been dropped for their unholy approach.
What kind of awe and trepidation do you suppose Aaron had toward the Lord and his own priestly office from that awful day forward? To approach the Holy God in the holiest place is a fearsome thing. In the days of the temple, on the Day of Atonement, the people would wait with bated breath wondering if the high priest would come out of the holy of holies at all, let alone alive. He is dangerous because He is holy. Our corrupt flesh cannot withstand unobstructed exposure to His glory; it would consume us.
Remember that after God evicted Adam and Eve from the garden, He placed cherubim with a flaming sword to guard the way to the tree of life. The image of cherubim was woven into the veil that separated the holy of holies from the holy place. They stood guard as if to say, “You have to get through us to get to Him.” The Life was on the other side. Nadab and Abihu were devoured by the flaming sword for having approached the Lord inappropriately. From the day sin came and man was evicted from the presence of God, the Lord said, “You cannot approach this Life. I told you that the day you ate of the fruit of the tree of knowledge of good and evil you would die. So you can’t have this life; you have sinned and must die.” You see, to approach this Life, to approach the living God, is a fearsome, fearsome thing that man can’t do without dying. Dead men see God. Living ones see Him only by His mercy.
Scripture abounds with examples of the hazards of approaching our Holy God with hubris. Korah’s co-conspirators, the men of Beth-shemesh, and the captains with their fifties all found out that our God is a consuming fire. Even in the transport of the Ark of the Covenant the sacred space of the holiest place wasn’t violated. Aaron and his sons would loose the veil from its hooks and walk it in to cover the Ark of the Covenant, essentially contracting the holy of holies to the outside dimension of the ark and the mercy seat. A covering of badgers’ skins was then spread over the veil upon which was placed a cloth of blue. Once these were securely wrapped about the ark, its staves were put in and it was ready for transit. And though the Levites bore it on their shoulders, they were not standing in the holy of holies. The high priest was the only person allowed to enter there, and that only once a year on the Day of Atonement.
 Read Num 3:38 again, this time in the KJV and then read Eph 2:12.
21 Kings 1:10; 1 Chr 21:26
 Lev 9:24
 This time the fire came from the holy of holies, not the sky. Here we may have the holy flamethrower (Lev 10:6)!
 Ezek 48:35
 Gen 3:22-24
 Ex 33:18-23
 Num 16:35-38
 1 Sam 6:12-20
 2 Kings 1:9-12
 Num 4:5-6