Shall ye keep mine ordinance - The only way to be preserved from all false worship is seriously to consider and devoutly to observe the ordinances of the true religion. He who in the things of God goes no farther than he can say, Thus it is written, and thus it behoves me to do, is never likely to receive a false creed, nor perform a superstitious act of worship.

1. How true is that word, The law of the Lord is Perfect! In a small compass, and in a most minute detail, it comprises every thing that is calculated to instruct, direct, convince, correct, and fortify the mind of man. Whatever has a tendency to corrupt or injure man, that it forbids; whatever is calculated to comfort him, promote and secure his best interests, that it commands. It takes him in all possible states, views him in all connections, and provides for his present and eternal happiness.

2. As the human soul is polluted and tends to pollution, the great doctrine of the law is holiness to the Lord: this it keeps invariably in view in all its commands, precepts, ordinances, rites, and ceremonies. And how forcibly in all these does it say, Thou shalt love the Lord thy God with all thy heart, and with all thy soul, and with all thy mind, and with all thy strength; and thy neighbor as thyself! This is the prominent doctrine of the preceding chapter; and this shall be fulfilled in all them who believe, for Christ is the end of the law for righteousness to them that believe.

Reader, magnify God for his law, for by it is the knowledge of sin; and magnify him for his Gospel, for by this is the cure of sin. Let the law be thy schoolmaster to bring thee to Christ, that thou mayest be justified by faith; and that the righteousness of the law may be fulfilled in thee, and that thou mayest walk, not after the flesh, but after the Spirit.

Therefore shall ye keep mine ordinance,.... Whatever the Lord appointed them and commanded, whether contained in this chapter, or elsewhere:

that ye commit not anyone of these abominable customs; for attending to the ordinances of God, and a close in them, they would be preserved from the commission of such abominable things, and giving in to such detestable customs as before warned against:

which were committed before you; by the inhabitants of Canaan; and by the punishment on them for them they might be deterred from doing the same:

and that ye defile not yourselves therein; for though the land is so often said to be defiled, yet, properly speaking, and chiefly, it was the inhabitants that were defiled by their abominable customs; and so would the Israelites also, should they observe the same, and thereby become abominable in the sight of God, and incur his displeasure, and be liable to his vengeance:

I am the Lord your God; who had a sovereign authority over them, and a right to give out what commands he pleased, both negative and affirmative; and to whom they were under obligations to obey, as the God of nature and providence, from whom they had their beings, and were supported in them, and as their covenant God, who had bestowed special and spiritual favours on them.

Therefore shall ye keep mine ordinance, that ye commit not any one of these abominable customs, which were committed before you, and that ye defile not yourselves therein: I am the LORD your God.

30. Therefore shall ye keep mine ordinance, that ye commit not any one of these abominable customs-In giving the Israelites these particular institutions, God was only re-delivering the law imprinted on the natural heart of man; for there is every reason to believe that the incestuous alliances and unnatural crimes prohibited in this chapter were forbidden to all men by a law expressed or understood from the beginning of the world, or at least from the era of the flood, since God threatens to condemn and punish, in a manner so sternly severe, these atrocities in the practice of the Canaanites and their neighbors, who were not subject to the laws of the Hebrew nation.

18:1-30 Unlawful marriages and fleshly lusts. - Here is a law against all conformity to the corrupt usages of the heathen. Also laws against incest, against brutal lusts, and barbarous idolatries; and the enforcement of these laws from the ruin of the Canaanites. God here gives moral precepts. Close and constant adherence to God's ordinances is the most effectual preservative from gross sin. The grace of God only will secure us; that grace is to be expected only in the use of the means of grace. Nor does He ever leave any to their hearts' lusts, till they have left him and his services.