Bird's-eye view
Here in the middle of the Holiness Code, we come to the section on clean and unclean animals. It is easy for modern Christians to dismiss these regulations as archaic, strange, or concerned merely with hygiene. While there are certainly hygienic benefits to following God's law, we must not miss the forest for the trees. The central point of these laws is theological. God is teaching His people how to make distinctions. Holiness is about separation, about cutting, about knowing the difference between the clean and the unclean, the sacred and the profane. These dietary laws were a daily, acted-out audiovisual aid, training the Israelites to see the world in terms of God's created order. When a creature conformed to that order, it was clean. When it blurred the categories, it was unclean. This principle, as we shall see, is a picture of sin and redemption.
This particular passage deals with a very specific class of creature: flying swarming things that also walk. Right away, we should see the potential for category confusion. And it is in this confusion that God teaches His people a crucial lesson about exceptions, redemption, and the nature of what is acceptable to Him. The rule is broad, but the exception is very specific, and it all points forward to the one who makes us clean.
Clause-by-Clause Commentary
v. 20 ‘All the swarming things that fly and that walk on all fours are detestable to you.
The Lord begins with a general principle. The category is sherets ha'oph, the flying creepers or swarmers. But there is a problem with them. They fly, which puts them in the category of birds, which are two-legged. But these creatures also "walk on all fours," which puts them in the category of land animals. This is a fundamental confusion of categories. They are hybrid creatures, anomalies in God's created order. They mix the heavens and the earth in a way that is contrary to the clear distinctions God established in Genesis. Birds fly and have two legs. Land animals walk and have four legs. These things try to do both, and so they represent a kind of created chaos. For this reason, they are declared sheqets, an abomination or a detestable thing. They are a living picture of what happens when God's boundaries are ignored. Sin is always a confusion of categories, with man trying to be God, and this law brings that principle down to the dinner table.
v. 21 Yet these you may eat among all the swarming things that fly and that walk on all fours: those which have above their feet jointed legs with which to jump on the earth.
But as with God's grace, there is an exception to the rule of condemnation. The general category is unclean, but God makes a provision for some to be counted as clean. Notice that God is the one who defines the exception. It is not up to the Israelites to decide which of these hybrid creatures seem "good enough." God gives a very specific anatomical marker: they must have jointed legs designed for jumping. This is not an arbitrary detail. These legs, the kera'ayim, are for leaping up from the earth. While these creatures crawl on the earth, they also possess a God-given ability to ascend, to spring upward. This is a picture of redemption. They are marked out from their detestable cousins by a feature that allows for a kind of transcendence. They are not entirely earthbound. This characteristic makes them acceptable, and it is a sign that points to the greater redemption we have in Christ, who makes us, who are creatures of the dust, able to ascend to the heavenly places.
v. 22 These of them you may eat: the locust in its kinds and the devastating locust in its kinds and the cricket in its kinds and the grasshopper in its kinds.
Here we have the specific examples of the clean, leaping insects. The law is not a vague principle; it is concrete. Locusts, crickets, grasshoppers, all in their various kinds, are declared edible. This is not just trivia for an ancient nomadic culture. This is the Word of God, and it has implications. We should immediately think of John the Baptist, that great Old Covenant prophet who came to prepare the way for the Lord. What was his diet in the wilderness? Locusts and wild honey (Matt. 3:4). This was not a sign that he was a strange outcast, living on whatever disgusting things he could find. Quite the opposite. John was demonstrating his profound covenant faithfulness. In the wilderness, away from the corruptions of the temple system in Jerusalem, he was eating food that was explicitly declared clean by the Mosaic law. He was a true Israelite, living a holy life of separation unto God, and his very diet was a testimony against a generation that had forgotten how to make the proper distinctions.
v. 23 But all other swarming things that fly and that are four-footed are detestable to you.
Lest anyone miss the point or try to broaden the exception, God concludes by restating the general rule. All the other flying swarmers, the ones that walk on four feet but do not have the special leaping legs, remain detestable. The default status for these category-confusing creatures is unclean. The exception is just that, an exception. This reinforces a central truth of the gospel. The default status for mankind, born in sin, is unclean. We are all creatures of the dust, crawling on our bellies, so to speak. Holiness is not our natural state. To be made clean requires a specific, gracious act of God. He is the one who provides the "leaping legs." He is the one who sets apart a people for Himself out of a condemned world. Without His specific, redeeming intervention, we all remain detestable in our sins.
Application
So what are we to do with a passage like this? We are not under the Mosaic dietary code. Christ, the Lord of the Sabbath and the Lord of the menu, has declared all foods clean (Mark 7:19). The curtain in the temple was torn from top to bottom, and the wall of separation between Jew and Gentile, with all its regulations, was torn down with it. The audiovisual aid has been fulfilled in the reality it pointed to.
But the principle endures. We are still required to be a holy people who make distinctions. The old covenant distinction was largely external, focused on what you ate. The new covenant distinction is internal, focused on what is in your heart, which then manifests itself in what you say and do. We are to distinguish between truth and error, between righteousness and unrighteousness, between light and darkness. We are to see the world as God's creation, with a given order and purpose, and we are to reject all the sinful attempts of our age to blur the lines and confuse the categories God has established, whether in marriage, sexuality, or the church.
And most importantly, we see the gospel here. We are the unclean, four-footed, swarming things, a confused mess of heaven-longing and earth-crawling. By nature, we are detestable. But God, in His mercy, sent His Son. In Christ, He has given us "jointed legs with which to jump." We have been crucified with Christ, and raised with Him, and seated with Him in the heavenly places. He is our redemption, the one who makes the exception for us, declaring us clean by His grace. Therefore, we are to live as clean people, not crawling in the dust of our old sins, but leaping up in joyful obedience and worship to the God who has saved us.