To begin with, it is worth starting with a definition. Experience teaches that not all believers understand the concept of the Mosaic Law in the same way. The definition I will be using in the further part of the lecture is as follows: the Mosaic Law (the Law) is a set of regulations that God transmitted through Moses for Israel to observe. Two observations arise from such a definition. First, the Decalogue recorded in Exodus 20:1-17 is part of the Mosaic Law. The fact that the Catholic Church instructs the faithful to memorize the Decalogue while omitting the rest of the regulations does not change the fact that the Decalogue, along with the other regulations delivered later, constitute a unity. Treating it separately has no justification in the Bible: both in the Old Testament, where Israel was obligated to observe all the regulations given by Moses, and in the New Testament, which uses a single Greek word Nomos whenever the Law is mentioned, without distinguishing the Decalogue in any way. Indeed, one can find in the Gospels and apostolic writings a division into the Law, Prophets, and Writings (a division introduced by Judaism, not by Christianity), but it pertains to the entirety of the books of the Old Testament. The concept of the Law in this context refers to the first five books, which we often call the books of Moses or the Torah (referring to the name of the Pentateuch in Hebrew).
Another artificial division consists in the separation of the Law into moral and ceremonial provisions. This approach was essentially introduced to justify why some rules are recommended for observance while others are not - because moral law is universal and continuously binding, while ceremonial law was given as a foreshadowing of the New Covenant. Since Jesus came and fulfilled the ceremonial law, his disciples no longer need to adhere to it. For example, we do not offer bloody sacrifices because they foreshadowed the sacrifice of the Savior's body. Since Jesus offered his body, this element of the Law no longer needs to be performed. Of course, I am repeating here arguments I have encountered over the years. However, I find no Biblical, logical justification for such arguments. It is true that some animal sacrifices foreshadowed the sacrifice of Jesus. But not all of them. Moreover, if our Lord fulfilled this element, freeing us from the ceremonies of the Law, why did he not fulfill the moral law in the same way? That we are bound by moral principles is evident from a number of passages in the New Testament. The assertion that Jesus freed us only from some regulations thus seems to be no more than an inconsistent attempt to justify how we can be clean before God today, while ignoring a significant portion of His Law.
In this lecture, I would like to present several perspectives on the issue of adhering to the Mosaic Law that appear in the New Testament. Considering them should provide the Reader with a clear answer to the question posed in the title. However, I want to clearly emphasize: the question is whether we are today obliged to observe the Law as a codified whole, every provision expressed within it. This does not mean that in the case of a negative answer, one should reject the entire Law or do everything the opposite way. The apostle Paul clearly states that sin is the source of death (Rom. 5:12). Therefore, if a Christian is obliged to follow the Law, any transgression will be a sin leading us to death. Thus, determining the answer to the question posed in the title is crucial for the practice of our faith. Below, I present several aspects of this topic addressed in the Bible from the perspective of a person believing in Christ:
Argument 1. The Mosaic Law resulted from the covenant made with the fleshly Israel
The Law Covenant, the result of which was the Law given through Moses, was established with fleshly Israel. This may be the most crucial piece of information for believers who are not carnal descendants of Abraham. The covenant was established on the night of the exodus from Egypt (Jer. 31:32, 34:13). The chosen nation was to be brought into the land of Canaan - a land flowing with milk and honey - but before they reached there, during a stop at Mount Sinai, God confirmed His covenant and gave Israel His law. The purpose of the Law was clearly expressed in the book of Deuteronomy: "Behold! I have set before you today life and good, and death and evil, (16) in that I command you today to love Jehovah your God, to walk in His ways, and to keep His commandments and His statutes and His judgments, so that you may live and multiply. And Jehovah your God shall bless you in the land where you go to possess it. (17) But if you turn away your heart, so that you will not hear, but shall be drawn away and worship other gods and serve them, (18) I declare to you today that you shall surely perish; you shall not prolong your days on the land where you pass over Jordan to go to possess it" (Deut. 30:15-18). Israel was therefore to take possession of the promised land forever and enjoy all God's blessings there, but on the condition of adhering to the Law.
Argument 2. A change of the priesthood means a change of the law
The Law of Moses thus had its clearly defined addressees and a clearly defined purpose. Even for this reason, the view that we today, not being descendants of Abraham, should be obligated to adhere to the Law, is incorrect - the parties to the Covenant of the Law were God and natural Jews. Non-Jews are not and have never been included in it. Doubt on this matter certainly partly arises from the fact that we believe in Jesus, who was a Jew raised under the Law. However, we are clearly informed that our Lord is the servant of another Covenant - the New Covenant. The Law Covenant was introduced by a mediator in the person of Moses with the Levitical priesthood. The New Covenant was introduced by the Mediator in the person of Jesus Christ with the priesthood "out of every kindred and tongue and people and nation" (Rev. 5:9-10; Heb. 9:15). Commenting on this change, the apostle Paul writes that "For the priesthood being changed, there is of necessity a change made in the law also" (Heb. 7:12). If our relationship with God is based on the New Covenant in the person of Jesus Christ, the Law of Moses serving another covenant does not apply here.
Argument 3. It is not possible to fully obey the Law
Another aspect of the matter is the impossibility of fully adhering to the regulations of the Law. James writes: "For whoever shall keep the whole Law and yet offend in one point, he is guilty of all" (Jas. 2:10). In order to enjoy righteousness based on the law, we would have to observe 100 per cent of its regulations at all times. No one has ever succeeded in this, with the only exception being our Lord (1 Pet. 2:21-25). Therefore, Paul declares in Gal. 3:10 - "For as many as are out of works of the Law, these are under a curse; for it is written, 'Cursed is everyone who does not continue in all things which are written in the Book of the Law, to do them'". Therefore, anyone who wants to justify themselves before God based on fulfilling the works of the Law is doomed to failure. We voluntarily submit ourselves to God's condemning judgment, wishing to present ourselves before God as keepers of the Law, because no one is able to fully observe the Law. And it’s not just about the 'moral law.' I previously wrote that the Law also covers ceremonies, sacrifices, etc. Today, no one observes these, even due to the lack of a proper place (the temple) where such sacrifices could be offered according to the Law. In the effort to keep the Mosaic Law, we are thus all — Jews and non-Jews alike — doomed to fail.
Argument 4. The law is not an effective means of reform/ does not lead to perfection
Treating the Law as a checklist, where we mark all items as completed and show God that we are righteous, will not lead us to the desired goal. But one can think of the Law as a means in that direction. Since a regulation is a repeatable procedure for conduct in certain circumstances, its repetition shapes certain habits of behavior in a person and teaches self-discipline. Thus, in this view, the Mosaic Law is a tool leading to perfection. We do not perform it perfectly, but through efforts in this direction, we shape character to one day achieve the goal of righteousness. The question then is, is there a chance that by following this path, one can actually achieve the goal of perfection? Here again, the apostle Paul gives a clear answer: "the Law made nothing perfect" (Heb. 7:19). This does not mean that the Law had no purpose in this regard; it did, but to a certain extent, to a certain point. The Law was meant to prepare Israel for the coming of the Messiah - it was he who was supposed to lead faithful Jews to perfection.
Argument 5. The Law led to Christ; Christ is not in addition to the Law, but instead of the Law
We clearly read about this in Gal. 3:23-25 - "But before faith came, we were kept under Law, having been shut up to the faith about to be revealed. (24) So that the Law has become a trainer of us until Christ, that we might be justified by faith. (25) But faith coming, we are no longer under a trainer". The purpose of the Law was thus partial. In His role as 'fulfiller of faith', Jesus not only does not act 'in addition' to the Law, but acts instead of it (Heb. 12:2). The New Covenant therefore signifies a change in the method of justification - a change that can be described as a transition from external motivation to internal motivation. The written code has been replaced by the Word of the Gospel working in hearts and minds. The apostle Paul writes: "For Christ is the end of the law for righteousness for everyone who believes. (5) For Moses writes of the righteousness which is of the Law, 'The man who does those things shall live by them.' (6) But the righteousness of faith says this: 'Do not say in your heart, Who shall ascend into Heaven?' that is, to bring Christ down; (7) or 'Who shall descend into the deep?'; that is, to bring up Christ again from the dead. (8) But what does it say? 'The Word is near you, even in your mouth and in your heart'; that is, the Word of Faith which we proclaim" (Rom. 10:4-8).
Argument 6. The New Testament explicitly commands the abandonment of the provision regarding circumcision
If the question in the title concerns whether we are obliged to follow every regulation of the Law, there is a provision that the New Testament explicitly instructs us to abandon: the provision concerning circumcision. Importantly, the case of circumcision is representative inasmuch as it was the first provision required by the Law to be performed on a newborn member of the chosen people or a proselyte. Without circumcision, observing other regulations made no sense. So what does the apostle Paul say about this fundamental obligation? "Stand fast therefore in the liberty with which Christ has made us free, and do not again be held with the yoke of bondage. (2) Behold, I, Paul, say to you that if you are circumcised, Christ shall profit you nothing. (3) For I testify again to every man that is circumcised, that he is a debtor to do all the Law, (4) you who are justified by Law are deprived of all effect from Christ; you fell from grace. (5) For we through the Spirit wait for the hope of righteousness out of faith. (6) For in Christ Jesus neither circumcision nor uncircumcision has any strength, but faith working through love" (Gal. 5:1-6).
Argument 7. Application of the Mosaic Law by believers leads to arbitrariness with regard to the commandments
In Col. 2:16-23, the apostle Paul presents a discussion concerning the observance of the Law, devoting considerable attention to the problem of arbitrariness in the execution of the law. In several ways, the apostle refers to this issue, accusing proponents of strict adherence to the Law of 'fleshly mind,' false humility, as well as practicing 'self-imposed worship,' which is 'according to the commands and doctrines of men' (Col. 2:18,22,23). This is an inevitable consequence of keeping the Law. Earlier in the lecture, I mentioned that there is nowhere today to offer the sacrifices required by the Law and no one to perform them because there are no priests. By observing the Law, we are thus compelled (arbitrarily) to acknowledge that these elements of the Law no longer apply. A similar problem arises with regard to the Ten Commandments. The Catholic Church advocates for the observance of the Decalogue, yet it is not common knowledge that the Decalogue as presented in the catechism is not the same Decalogue that Moses received. The Church changed the commandment concerning the observance of the Sabbath to the commandment to 'keep the holy day,' while the commandment prohibiting the making and worship of images was completely removed. Since the last commandment was split into two, the Catholic Church still has ten of them. This can be done too – but what is the point?
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The above does not exhaust the issue of Christians observing the Mosaic Law. However, in this lecture, I aimed at focusing on the most obvious, explicitly stated aspects of the matter. In the conclusion, I would like to refer to a general principle related to observing the law. Its advocates point out that Jesus also referred to its provisions as binding. An example can be found in the story described in Mt. 19:16-22 - "And behold, one came and said to Him, Good Master, what good thing shall I do that I may have eternal life? (17) And He said to him, Why do you call Me good? There is none good but one, that is, God. But if you want to enter into life, keep the commandments. (18) He said to Him, Which? Jesus said, You shall not murder, you shall not commit adultery, you shall not steal, you shall not bear false witness, (19) honor your father and mother, and, you shall love your neighbor as yourself. (20) The young man said to Him, I have kept all these things from my youth up; what do I lack yet? (21) Jesus said to him, If you want to be perfect, go, sell what you have and give to the poor, and you shall have treasure in Heaven. And come, follow Me. (22) But when the young man heard that saying, he went away sorrowful; for he had great possessions".
Jesus therefore indicates that the condition for obtaining eternal life is to keep the commandments (Mt. 19:17) - evidently the commandments of the Mosaic Law. However, we must separate the content of the law from its source. The Education System Act of 1991, which for many years was the basic legal act regulating the education system in Poland, contained many provisions that, during the 2017 reform, were "cut out" and literally included in the Education Law. In 2025, we still apply these provisions, but this does not mean that we apply the Education System Act in this way. We do in fact apply the Education Law, although the content of the provision is much older than the law itself. The same applies to the Mosaic Law – many of its provisions are repeated in the New Testament, as they are derived from universal ethical principles. However, this does not mean that the entire Mosaic Law is in force. In addition to referencing universal content, the Mosaic Law also contained a number of regulations tailored to a specific time, place, and, above all, nation. Applying them without considering these circumstances may not provide the expected benefits to subjects of the Law acting on their own initiative.