Leviticus 8-10: The Holy and the Common

Then the LORD said to Aaron,  “You and your sons are not to drink wine or other fermented drink whenever you go into the Tent of Meeting, or you will die. This is a lasting ordinance for the generations to come. You must distinguish between the holy and the common, between the unclean and the clean, and you must teach the Israelites all the decrees the LORD has given them through Moses.” - Lev. 10:8-11 NIV

You would not expect tragedy to fall upon Aaron, the High Priest, chosen and ordained by God.  Only good things should follow him.  But, her was only human after all and so were his sons.  None of them had the close relationship with God that Moses had.  None of them heard the Lord's voice, so it's possible that they didn't truly believe Moses when he told them what the Lord required.

Whether they believed or not, God's commands were true and final.  They were to distinguish between the holy and the profane.  It was a matter of life and death.

How often do we confuse the profane (or common) for something that is holy.  How often do we offer sacrifices that are not what God requires?  Do we wave our unauthorized censers before him and expect results?  If we are wise, unlike Aaron's sons, Nadab and Abihu, we would acknowledge that we are lucky to escape with our lives.  Such is the consequence of not understanding the difference between the holy and the profane.  The common is thought up by man, while the holy is ordained by God.