Leviticus 10:3: Then Moses said unto Aaron, this is it that the Lord spake, saying, I will be sanctified in them that come nigh me, and before all the people I will be glorified. And Aaron held his peace.
The children of Aaron sinned before God by causing their own fire to come up before the presence of God. This brought upon them the wrath of God and they died on the spot. They were sanctified to minister before God, but when they broke the laws of God, God had to sanctify Himself before them by not allowing them to do what they pleased. He did not accept their fake fire and had to deal severely with them.
Just because we are the children of God or accepted by God by His grace and mercy, it does not mean that we can do what we want and fool around with God. We are called to be holy and to be faithful in His presence. We are accountable for our life and what we do with it every single day. Remember that we are supposed to be answering God for how well we conducted our life here on earth. God is not a respector of persons. He is fair in His judment and His trial. That is why He had to punish the sons of Aaron even though they were the priest’s kids.
It would be good if we cross examine our lives every day. How we start our day and how we end our day is of importance to God. What we do with us and others with our life also matters to God. Let us not take God for granted. Live in the reverential fear of God and strive to be what He wants us to be. Live a life that brings glory and honor to our Creator.