The Tabernacle, a Shadow of Christ
This passage deals with Jesus driving out the money changers and merchants who had turned the temple into a marketplace, pointing out the reality that the temple had fallen from a house of prayer into a place of trade. Amid the corruption of priests who exploited the pilgrims' offerings and let only blemished sacrifices pass, Jesus would not tolerate the defiling of God's house. This is no different from the world's attitude of using God for its own gain without knowing his grace, and it shows how precious true worship is.
And through the incident in which Aaron's sons Nadab and Abihu offered strange fire without being commanded and were put to death, it warns that even with an office and its robes, one cannot stand before God without changing the habits of one's life. They forgot the holiness of being priests and could not let go of worldly ways of thinking, which led them to despise the ordinances God had set. This was not simply a ceremonial mistake; it was a judgment that came because their character had not changed even after meeting God, and their faith was lacking.
The sermon asks how believers should live so as not to stain the robe of righteousness they have put on. It leads us to reflect on what it means to come to worship not treating God's work as a position or a paycheck, but believing in the grace of the cross and loving and honoring God with a heart that allows no margin of error.