John Calvin Commentary Leviticus 10:1

"And Nadab and Abihu, the sons of Aaron, took each of them his censer, and put fire therein, and laid incense thereon, and offered strange fire before Jehovah, which he had not commanded them." — Leviticus 10:1 (ASV)

And Nadab and Abihu, the sons of Aaron. A memorable circumstance is recorded here, from which it appears how greatly God abominates all the sins by which the purity of religion is corrupted.

Apparently, it was a light transgression to use strange fire for burning incense. Again, their thoughtlessness would seem excusable, for Nadab and Abihu certainly did not wantonly or intentionally desire to pollute the sacred things. However, as is often the case in new matters, when they were undertaking them too eagerly, their hastiness led them into error.

The severity of the punishment, therefore, would not please those arrogant people who do not hesitate superciliously to criticize God’s judgments. But if we reflect on how holy a thing God’s worship is, the enormity of the punishment will by no means offend us.

Besides, it was necessary that their religion should be sanctioned at its very beginning. For if God had allowed the sons of Aaron to transgress with impunity, they would have afterward carelessly neglected the whole Law.

This, therefore, was the reason for such great severity: that the priests should anxiously watch against all profanation.

Their crime is specified, namely, that they offered incense in a different way from that which God had prescribed. Consequently, although they may have erred from ignorance, they were still convicted by God’s commandment of having negligently handled what was worthy of greater attention.

The “strange fire” is distinguished from the sacred fire which was always burning on the altar: not miraculously, as some pretend, but by the constant watchfulness of the priests.

Now, God had forbidden any other fire to be used in the ordinances, in order to exclude all extraneous rites and to show His detestation of whatever might be derived from elsewhere.

Let us learn, therefore, to pay such close attention to God’s command as not to corrupt His worship with any strange inventions.

But if He so severely avenged this error, what a horrible punishment awaits the Papists, who are not ashamed obstinately to defend so many gross corruptions!