In the Old Testament, there is an unusual story about two young men who died while worshipping God. Nadab was the firstborn son of Aaron, the Israelites’ High Priest; Abihu was his younger brother. Leviticus 10 explains how these two men followed their own desires, rather than doing what God had commanded.
"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. And there came forth fire from before Jehovah, and devoured them and they died before Jehovah" (Leviticus 10:1-2).
This is a scary story, wouldn’t you say? Nadab and Abihu apparently must have done something really bad, because God caused fire to leap from the altar and consume them! Why did this happen? The key to understanding the story lies in the fact that they offered "strange fire" that God "had not commanded." What does the Bible mean when it speaks of "strange" fire? Perhaps we can understand this point better by looking at other passages in the Old Testament that discuss worship to God. There is a good example in Exodus 30:9 where God gave the Israelites specific instructions regarding the altar of incense. He warned them: "You shall not offer strange incense on it, or a burnt offering, or a grain offering; nor shall you pour a drink offering on it."
God told the Israelites exactly what kind of incense they were to burn during their worship of Him (read Exodus 30:7-8). Anything else was "strange" incense that God had not authorized, and therefore violated God’s law. In Leviticus 16:12, we learn where Nadab and Abihu should have gotten the fire they used in their worship. "Then he shall take a censer full of burning coals of fire from the altar before the Lord." Aaron’s two sons ignored Jehovah’s law and obtained the fire they used from somewhere else. This was a terrible sin that ultimately cost them their lives!
In referring to the Old Testament, the apostle Paul commented: "For whatsoever things were written aforetime were written for our learning," (Romans 15:4). From the account of Nadab and Abihu, we can learn a really important lesson regarding how God wants us to worship Him. That lesson is this: God expects us to obey Him—not just in how we worship, but in every aspect of our lives.
Does God want us to be sincere in what we do? Yes, indeed. But it is not enough to be just sincere. We also must do exactly what God has commanded, in exactly the way He has commanded that we do it. Nothing can take the place of simple obedience to God. Therefore, let us all try not only to worship and serve God, but also to worship and serve Him in a scriptural manner as He has commanded.