It's interesting that they acknowledge in the SS quarterly the artificiality and convenience of their separation of the law. Official Adventist publications don't often do that, at least from what I've observed. The realization that the ancient Jews didn't classify the law into separate "moral" and "ceremonial" categories was what initially led me to question the Adventist view of the law and the Sabbath.
I see that in the SS lesson, they list five categories: "(1) moral law, (2) ceremonial law, (3) civil law, (4) statutes and judgments, and (5) health laws." Throughout my experience in Adventism, I most often heard about the "moral" and "ceremonial" laws and only occasionally heard references to the other categories. Some Adventists talk about a "natural law" as well, into which category they place EGW's dietary instructions; I guess that would be the same as the fifth category listed in the lesson.
Also, I find it ironic that the concept of the division of the law into "moral," "ceremonial," and "civil" categories has its origins in the writings of Thomas Aquinas, a Catholic theologian. From his
Summa Theologica (articles 3 and 4):
On the contrary, It is written (Dt. 4:13, 14): "Ten words . . . He wrote in two tables of stone; and He commanded me at that time that I should teach you the ceremonies and judgments which you shall do." But the ten commandments of the Law are moral precepts. Therefore besides the moral precepts there are others which are ceremonial.
I answer that, As stated above (A[2]), the Divine law is instituted chiefly in order to direct men to God; while human law is instituted chiefly in order to direct men in relation to one another. Hence human laws have not concerned themselves with the institution of anything relating to Divine worship except as affecting the common good of mankind: and for this reason they have devised many institutions relating to Divine matters, according as it seemed expedient for the formation of human morals; as may be seen in the rites of the Gentiles. On the other hand the Divine law directed men to one another according to the demands of that order whereby man is directed to God, which order was the chief aim of that law. Now man is directed to God not only by the interior acts of the mind, which are faith, hope, and love, but also by certain external works, whereby man makes profession of his subjection to God: and it is these works that are said to belong to the Divine worship. This worship is called "ceremony" [the munia, i.e. gifts] of Ceres (who was the goddess of fruits), as some say: because, at first, offerings were made to God from the fruits: or because, as Valerius Maximus states [*Fact. et Dict. Memor. i, 1], the word "ceremony" was introduced among the Latins, to signify the Divine worship, being derived from a town near Rome called "Caere": since, when Rome was taken by the Gauls, the sacred chattels of the Romans were taken thither and most carefully preserved. Accordingly those precepts of the Law which refer to the Divine worship are specially called ceremonial.
Reply to Objection 1: Human acts extend also to the Divine worship: and therefore the Old Law given to man contains precepts about these matters also.
Reply to Objection 2: As stated above (Q[91], A[3]), the precepts of the natural law are general, and require to be determined: and they are determined both by human law and by Divine law. And just as these very determinations which are made by human law are said to be, not of natural, but of positive law; so the determinations of the precepts of the natural law, effected by the Divine law, are distinct from the moral precepts which belong to the natural law. Wherefore to worship God, since it is an act of virtue, belongs to a moral precept; but the determination of this precept, namely that He is to be worshipped by such and such sacrifices, and such and such offerings, belongs to the ceremonial precepts. Consequently the ceremonial precepts are distinct from the moral precepts. . . .
On the contrary, It is written (Dt. 6:1): "These are the precepts and ceremonies, and judgments": where "precepts" stands for "moral precepts" antonomastically. Therefore there are judicial precepts besides moral and ceremonial precepts.
I answer that, As stated above (AA[2],3), it belongs to the Divine law to direct men to one another and to God. Now each of these belongs in the abstract to the dictates of the natural law, to which dictates the moral precepts are to be referred: yet each of them has to be determined by Divine or human law, because naturally known principles are universal, both in speculative and in practical matters. Accordingly just as the determination of the universal principle about Divine worship is effected by the ceremonial precepts, so the determination of the general precepts of that justice which is to be observed among men is effected by the judicial precepts.
We must therefore distinguish three kinds of precept in the Old Law; viz. "moral" precepts, which are dictated by the natural law; "ceremonial" precepts, which are determinations of the Divine worship; and "judicial" precepts, which are determinations of the justice to be maintained among men. Wherefore the Apostle (Rom. 7:12) after saying that the "Law is holy," adds that "the commandment is just, and holy, and good": "just," in respect of the judicial precepts; "holy," with regard to the ceremonial precepts (since the word "sanctus"---"holy"---is applied to that which is consecrated to God); and "good," i.e. conducive to virtue, as to the moral precepts.
Perhaps Adventism traditionally has followed more closely in the footsteps of Catholicism than they realize.