Lethal Worship of God
In Parshas Shemini, we read about a special Korban to Hashem that Ahron and his sons brought after meticulously carrying out all of the actions necessary for this Korban. Hashem showed a sign of acceptance for the Korban and it was a time of celebration for the Jewish people. During this time of celebration, Ahron’s sons, Nadav and Avihu brought a “strange fire” before Hashem that He had never commanded them to bring. Hashem punished them through a fire that consumed them.
The pasuk is unclear what their sin was, commentators give their own ideas about the issue of their actions. What is interesting is that in every explanation, their intent was for showing gratitude to Hashem, like they had just done before. Why would they be punished so harshly for their actions if their true intent was for service of God?
The answer to why these great people deserved death lies in the fact that only Hashem knows how we should properly serve him. When we project our own emotional fantasies onto the service, it becomes avodah zarah. The same word “zarah” used to reference their fire— “Aish Zara”—is also the word used in idol worship, “avodah zarah”.
Rashi (Num. 10:2) offers two opinions why Nadav and Avihu were killed. According to these opinions—they ruled in front of Moshe, or they served God while drunk—they were dismissive of Torah authority. By offering a strange fire, they believed they knew how to serve Hashem without His guidance, and by ruling in front of Moshe they rejected his authority.
Death was an appropriate response for their sin, because they were changing God’s will, which is the basis of Avodah Zara, which we punish with death. In Hilchos Avoda Zara 1:1 Rambam teaches that the original star worshipers did not deny God’s existence, rather: “All mankind knew that God is unique alone. Rather, their mistake and their foolishness was that they imagined that star worship is God's will.”