The reason that Nadab and Abihu were killed is because they offered "strange fire", rather than the "pure" fire from the brazen altar.
Lev 10:1 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.
Lev 10:2 And there went out fire from the LORD, and devoured them, and
they died before the LORD.
Lev 10:3 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.
Lev 10:4 And Moses called Mishael and Elzaphan, the sons of Uzziel the
uncle of Aaron, and said unto them, Come near, carry your brethren from
before the sanctuary out of the camp.
Lev 10:5 So they went near, and carried them in their coats out of the
camp; as Moses had said.
Looking back we see that the Lord had just done a great thing:
Lev 9:23 And Moses and Aaron went into the tabernacle of the
congregation, and came out, and blessed the people: and the glory of
the LORD appeared unto all the people.
Lev 9:24 And there came a fire out from before the LORD, and consumed
upon the altar the burnt offering and the fat: which when all the
people saw, they shouted, and fell on their faces.
There had just been a great manifestation of God, but Nadab and Abihu, instead of obeying God, decided to do things their way, and for their efforts incurred the wrath of Jesus.
But what exactly was their error? The Bible teaches that the content of the incense that would be offered to God had to be just so:
Exo 30:9 Ye shall offer no strange incense thereon, nor burnt sacrifice, nor meat offering; neither shall ye pour drink offering thereon.
Apparently the incense that Nadab and Abihu used was OK. They did not offer "strange incense". The censers that they used were not the problem. Let us look at why they were destroyed.
Lev 10:1 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.
The problem was "strange fire". They were supposed to get the fire for their censers from the brazen altar. The brazen altar was the altar where sacrifices or "sin offerings" were made. It is regarded as a "type and shadow" of the first step in the plan of salvation which is repentance.
Notice that Acts 2:38 is for all that God will call.
Acts 2:39 For the promise is unto you, and to your children, and to all that are afar off, even as many as the Lord our God shall call.
Heb 10:1 For the law having a shadow of good things to come, and not the very image of the things, can never with those sacrifices which they offered year by year continually make the comers thereunto perfect.
Just as Nadab and Abihu tried to worship God their own way and BYPASS the brazen altar and offer "strange fire"; the modern day charismatics bypass repentance and Jesus Name baptism trying to worship God their own way while still being "of the world".
By living worldly and refusing to repent they offer "strange fire" unto the Lord. That is why real Acts 2:38 Christians do not accept the charismatic cults as brethren even if they do obey part of the plan of salvation.
"Almost christian" cults will not even "almost" go to heaven. They offer "strange fire", they don't want the original Apostolic way, though they like the spectacular as did Nadab and Abihu.
Don't be deceived in a charismatic cult. Find a real Apostolic, Pentecostal Church that doesn't offer a sin leavened "strange fire" unto the Lord.
1 Cor 5:6 Your glorying is not good. Know ye not that a little leaven leaveneth the whole lump?
Be faithful!
Rev. Steve Winter