Aaron's sons Nadab and Abihu took their censers, put fire in them and added incense;
and they offered unauthorized fire before the LORD,
contrary to His command.
So fire came out from the presence of the LORD and consumed them, and they died before the LORD.
Leviticus 10:1-2, NIV
There might be times that we are tempted to wonder, "So, what's the big deal?" We might wonder why we cannot just skip worshiping on the first day of the week. We might wonder if we really have to take the Lord's supper every first day of the week. We might wonder if God really means it when He tells us not to misuse His name. We might think that little white lies do not count when He promises that all liars will go to Hell. We might think that sprinkling is as good as immersion, that the man made "believer's prayer of faith" is just as good as obedience, and that approaching God in any old way will do just so long as we say that we love Him.
But note what happened in the passage above: In Leviticus 8 and 9 we have no fewer than 10 passages that mention the LORD's commands, and each time, Aaron, Moses, Nadab and Abihu obey those commands. But just one time, in Leviticus 10:1, do we read that the LORD's command was not carried out, and we find that God struck Nadab and Abihu dead for that one transgression.
They, too, might have wondered, "So, what's the big deal?" They might have thought that 10 out of 11 wasn't bad when it came to obeying the LORD's commands, but they were wrong!
Are you... willing to take that risk today? This is why we study!
"Not everyone who says to Me, "Lord, Lord" will enter the kingdom of heaven, but only he who does the will of My Father Who is in heaven."
Matthew 7:21, NIV
Today is the 19th day of the 30 day challenge to study through the Books of Moses, with Leviticus 8-10 being the text for today. May God richly bless you as you seek to find His entire will and obey it!