What are the holy things? What are the pearls? For a follower of Jesus, nothing is more precious than the gospel of Jesus Christ. The fundamental idea in the word holy, as Ed Welch traces it back through Leviticus, is being set apart for God. Welch points to Leviticus 10:10, where God tells his people to distinguish between the holy and the common, the clean and the unclean. With those four categories, God gives us the basic building blocks of his spiritual universe.
To take what God has set apart and hand it over as if it were nothing has a name in Scripture, and that name is profane. Jesus reaches for the most valuable image his hearers knew to show how precious these things are. In the ancient world pearls were prized above diamonds, the very epitome of luxury. The gospel, the truth of the kingdom, the treasures of your Father in heaven, these are the pearls. They are worth more than anything you own.
Before you ever think about who might trample the gospel, let the weight of its worth land on you. Keener and Morris remind us that this verse only makes sense once you feel how holy and how costly these pearls are. You are guarding treasure, not opinions.