In the last of his 3 major works, Moreh Nevuchim, Rambam presents many of his philosophical views, as well as his meta-views of the Halachic system. Though many great Rishonim reject attempts at providing Ta’amei HaMitzvot (reasons for the Mitzvot), Rambam clearly believes that understanding them is an important pursuit. It is for this reason that he spends a tremendous portion of the guide explaining why Hashem commanded the laws that He did.
In Moreh Nevuchim (3:32), Rambam explains why Hashem commanded us to bring Korbanot, animal sacrifices, in the Beit HaMikdash. He prefaces the discussion with general remarks about the gradual development of organisms. As an example, he explains that a newborn is quite tender and cannot be fed dry food. Therefore, “breasts were provided which yield milk, and the young can be fed with moist food which corresponds to the condition of the limbs of the animal.” This demonstrates God’s wisdom in creating human beings in such a way that newborns can survive.
In a similar manner, Rambam explains the laws of Korbanot. The main purpose of the law, Rambam explains, is to make us a holy nation that recognizes Hashem. He explains that Hashem sent Moshe to take us out of Egypt so that we would become a nation of holy people who would serve Hashem (Shemot 19:6) and do so wholeheartedly.
Rambam establishes a chief objective of Halachah as serving Hashem. He explains that the custom of all religious people in ancient times was to serve their god/gods with animal sacrifices, so commanding Bnei Yisrael not to do so would be analogous to a prophet in our days telling us to serve Hashem with thought alone, and not to pray, fast, and call out in times of trouble. The form of service, though secondary to the primary objective, is reflective of the common form of service that existed at the moment that the law was commanded. Since the common practice included animal sacrifice, Hashem transformed his service into one which consisted of the common religious services of that time. Rambam writes (Moreh Nevuchim 32) the following:
“By this Divine plan it was effected that the traces of idolatry were blotted out, and the truly great principle of our faith, the existence and unity of God, was firmly established; this result was thus obtained without deterring or confusing the minds of the people by the abolition of the service to which they were accustomed and which alone was familiar to them.”
Rambam provides a concrete ramification, or Nafka Minnah, of the fact that Korbanot are not the primary purpose of the law, and they are even not as near to the objective as prayer and supplication. Since Korbanot are not ideal, the obligation of Korbanot has been restricted to the place of the Beit HaMikdash, and specifically to the Kohanim, but the obligation of prayer has been included to all people in all places.
Rambam then explains the verse in Yirmiyahu, in which the prophet scolds the people for their abundant sacrifices and tells them that their ancestors were not commanded to bring Korbanot (Yirmiyahu 7:22-23). How could Yirmiyahu make this claim if Hashem did command the offering of animal sacrifices? Rambam explains that Yirmiyahu is alluding to the distinction between the primary and secondary purpose of the law. Korbanot are the secondary objective, but it serves to underscore a principle of service to Hashem. Yirmiyahu’s constituents, though they continued to sacrifice in the Beit HaMikdash, failed to realize the ultimate purpose of sacrifices as a rejection of idolatry and an affirmation of Judaism.
To summarize, Rambam believes that Korbanot were commanded as a means of service because the people of the time were accustomed to such a practice. They are not the primary objective of the law, which is why only specific people in a specific place can bring them. Additionally, they are meaningful and desired by Hashem only when the person bringing the Korban realizes the true purpose of performing the sacrifice.
We may pose two important additional issues regarding Korbanot: whether they are inherently undesirable, and whether they will be applicable in the days of Mashiach. This will then serve as the basis for a discussion about the difference between the primary and secondary objectives of Halachah.
I think many would advance the following claim: Since Hashem commanded Korbanot only because it was the common practice of the time, not because they are inherently significant, we see that Korbanot are undesirable. This, however, does not follow from Rambam’s words. What emerges from his comments is that Hashem’s system of law caters to the condition of mankind. We should expect nothing less of a system that is designed to be upheld and supported by man. Rambam even says that Hashem “transferred to His service that which had formerly served as a worship of created beings, and of things imaginary and unreal, and commanded us to serve Him in the same manner” (Moreh Nevuchim 32). By commanding Bnei Yisrael to bring animal sacrifices, Hashem made an action of idolatry into an action of service. Once it is an act of direct service of Hashem, it is hard to see how we can still call it undesirable.
In terms of application in the days of Mashiach, nothing follows from Rambam’s comments in the guide. What seems clear is the following: were God to give us the Halachic system now, it would exclude animal sacrifice. We are unaccustomed to animal sacrifice, so there would be no reason for Hashem to include it in the law. But that counterfactual says nothing regarding whether the law of Korbanot will remain the same or not in the days of Mashiach. That is a completely separate question of whether the system of Halachah will change in the days of Mashiach. Conveniently, Rambam tells us his opinion on this matter quite explicitly; in Hilchot Teshuvah 9:2, he describes the state of the world in the days of Mashiach as being almost identical to our current lives; the only difference is that Bnei Yisrael will self-govern in the days of Mashiach. [Moreover, Rambam in Hilchot Melachim 11:1 and in Ma’aseh HaKorbanot 2:14 explicitly writes that Korbanot will apply in the days of Mashiach.]
Finally, Rambam’s comments allude to a two-tiered system of Halachah, with a primary objective and a secondary level. It seems that the primary tier is the level of principles and ideals. Included in this tier are things that aim at the ultimate goods in this world. Examples would be good relations among people, limiting desires within people, knowledge of Hashem, service of Hashem, etcetera. There is a second tier, which we know as the 613 Mitzvot. These are secondary in nature since they are the means at achieving the end. Rambam explains that prayer and Teshuvah are nearer to the objective of service of God than is the act of animal sacrifices. Meaning, certain tier two Mitzvot can achieve tier one ideals better and more directly than others.
When Chazal wrote that Torah preceded the creation of the world, they probably were referring to the concepts and ideals included in tier one. The creation of tier two happened at Har Sinai when Hashem decided which laws would best aim at achieving tier one. What is included in tier two laws was decided based on the state of the people at the time of Har Sinai, but they apply through the days of Mashiach, according to Rambam. Rambam’s approach to the laws of animal sacrifice thus gives us a deep insight into the entire system of Halachah.
 This is not an original opinion of his; the Gemara Sanhedrin 91b records this opinion in the name of Shmuel. Rambam also quotes the opinion in Hilchot Melachim 12:2. It is important to note that Rambam himself does cite other differences. In Hilchot Ta’aniot 5:19, he writes that the fast days will be cancelled in the days of Mashiach and will transform into Yamim Tovim. In Hilchot Megillah VeChanukah 2:18, he writes that all of Nevi’im and Ketuvim, other than Megillat Ester, will be Bateil (null) when Mashiach comes. In Hilchot Shemitah VeYovel 13:1, Rambam mentions that we will add more Arei Miklat in the days of Mashiach. He mentions this again in Hilchot Rotzei’ach 8:4. The sense from the Rambam is that the differences are few and far between. Moreover, there is not even one Mitzvah which will be added or removed when Mashiach comes.
 It could also refer to a “right” to marry the young man who visited her.
 The Beth Din of America’s Geirut Policies and Standards document states (following the approach of the Beit Yosef):
“Where marriage to a particular Jewish partner is a major incentive to a prospective conversion, there is an increased possibility that the Geirut may come with less than the complete commitment necessary for a conversion that would be in keeping with the standards we are trying to set for the regional Batei Din. Nonetheless, experience also shows that such a motivation can result in converts of the highest caliber. Conversion for the sake of marriage therefore requires the partner are likely to subscribe to the requisite beliefs and practices. The Beit Din must be convinced that if the potential spouse were to disappear from the candidate’s life, his or her commitment to the Jewish faith and people would not waver. These factors inevitably prolong the process and make examination of the prospective convert more intense. Indeed, should the couple mention a proposed wedding date as a deadline or goal, the Beit Din should respond that the process will take significantly longer than that.”
 For example, his commentary to Yeshayahu 11:1