In chapter 8 of Leviticus, Moses acts out the ordination rites that were prescribed by God, and he ordained Aaron and his sons to the Levitical priesthood. Now in chapter 9, after seven days of being somewhat quarantined in the tabernacle, Aaron is being installed as the high priest. This is the eighth day since the ordinations began, so just like with circumcising a baby and even Jesus rising on Sunday, the eighth day represents new creation.
Aaron offers the sacrifices for the first time as high priest, this is a new creation and a ratification of the covenant that God gave to Moses on the mountain. All the offerings were performed and when Moses goes into the tabernacle with Aaron, and when they come out of it God sends fire down from heaven to consume the sacrifices and show his approval of what has taken place.
This leads to the events of chapter 10. Here we see two of Aaron’s sons, Nadab and Abihu, take their censers and lay incense in it, with coals of fire, and offer this as an offering of incense to God. Immediately they are consumed by fire because God did not approve of what happened.
So why are they killed? The text here only says it was because of the ‘unholy fire’ in the RSV, but some others translate it as ‘strange fire’ or ‘impure fire’ but it doesn’t say what made it strange, impure or unholy. There’s no commentary by Moses explaining exactly why this happened, and really as the creator of the universe God owes us no explanation for anything, but it would be nice to know so we possibly don’t make the same mistake or can learn from it somehow.
There are two leading theories on what happened here. One is that the two sons were drunk when they went into the tabernacle and offered the incense. This is because a few verses from now, after Aaron and his surviving sons are warned not to leave the tabernacle to mourn the dead family members, they are given a new prohibition against drinking while on duty (verse 9). Some take this to be directly connected to the sons and their death, so that being drunk on duty was such a crime that they were slain.
Another theory is that God had given no instructions on this type of offering yet, and so they took it upon themselves to do this and were speaking on behalf of God. They were inventing this new liturgical action and that is the prerogative of God. Later in Leviticus, God does give instructions for a sacrifice similar to this one and the coals for the incense are to be taken from the altar of burnt offerings. So it’s possible that this instruction was already known to them, even though we haven’t read it yet, and they disobeyed it. They are told to boil the meat of one of the sacrifices to then consume it, and this is not done on the altar, so there is other sources of fire available in the courtyard of the tabernacle.
In the end we don’t know exactly what made the fire unholy, but we know what the consequences of mixing holy and profane things, and the consequences of not taking liturgy seriously. Obviously we don’t see priests consumed with fire from heaven when they go outside the liturgy, but we should still take the things of God, including worship of him, very seriously and with reverence.
Chapter 11 then closes out our Old Testament readings today by going through a list of the unclean and clean animals. These animals were set aside as out of bounds for the Israelites to set them apart and make them distinct. So many ceremonial rules were to get the Israelites separated from the pagan nations around them, to make them feel in their day to day lives that they were different, to keep them away from their culture and their gods. This was all a setup to prepare the people for the eventual coming of the messiah and his gospel.