Why did Nadab and Abihu do this irreverent deed and why did God kill them for doing it? Many suggest that Nadab and Abihu were drunk (and perhaps they were), but the root of their sin was unquestionably pride. Their behavior, fueled by a flawed awareness of their own self-importance, was arrogant. They had lost their perspective of who God is and where they stood in relationship to Him. It is for this reason God said that He must always be regarded as holy and that He alone must be glorified.
I am the Lord, that is My name; And My glory I will not give to another… Isaiah 42:8a
God is Serious
God is very serious about holiness and glory, so much so that He devoured Nadab and Abihu by fire as a perpetual example for us. If mere words had been sufficient, Nadab and Abihu would not have died (for these were things that they knew). We might then ask, “Why does God want all the glory for Himself—is God selfish? This is not the case; God is not egocentric.
God Knows That…
When man gets the glory, or a ministry, or a church, those things will eventually come to disappoint and frustrate us. If we suffer discontentment chances are we have become enamored in the temporary splendor of man or ourselves. God knows these things and this is precisely the reason He demands the glory must be His alone. In Him, no one is ever saddened or dissatisfied.
If we are faithless, He remains faithful; He cannot deny Himself. 2 Timothy 2:13
He Dwells -- The B'log in My Eye 