In the third month after the exodus from Egypt, Moses goes up to Mt. Sinai and receives instruction from the Lord of what he is to say to the house of Jacob and the sons of Israel:

"'You yourselves have seen what I did to the Egyptians, and how I carried you on eagles' wings, and brought you to Myself. Now then, if you will indeed obey My voice and keep My covenant, then you shall be My own possession among all the peoples, for all the earth is Mine; and you shall be to Me a kingdom of priests and a holy nation.' These are the words that you shall speak to the sons of Israel." (Ex 19:4-6)

Those who believe that God is a real Being and developed a trust to obey His voice and keep His covenant would be His own possession and a priest.

The record of God's discourse with Moses becomes the collection of books called the Pentateuch or what Jews called the Torah. They are the only books that record God's personal words, which is in contrast to the rest of the Bible authored by prophets superintended by the Holy Spirit.

In his letter to Believers in Pontus, Galatia, Cappadocia, Asia, and Bithynia, Peter writes a letter of encouragement to "long for the pure milk of the word, so that by it you may grow in respect to salvation" (1 Pet 2:2), which serves as a basis for a life in pursuit of holiness that is detailed throughout the letter. Peter writes that they, "as living stones, are being built up as a spiritual house for a holy priesthood" (1 Pet 2:5).

But you are a chosen people, a royal priesthood, a holy nation, a people for God's own possession, so that you may proclaim the excellencies of Him who has called you out of darkness into His marvelous light; for you once were not a people, but now you are the people of God; you had not received mercy, but now you have received mercy. (1 Pet 2:9-10)

Just as in the Old Testament, this confirms that genuine Believers of the New Testament are God's own possession and a part of His royal priesthood.

The Pentateuch / Torah is essential to the understanding of the whole Bible, because without understanding these 5 books, one could not make sense of the Bible. The Pentateuch / Torah is significant for:

1. How the world, life, and human beings, male and female, came to be (Gen 1 - 2).

2. How sin and death entered into the world (Gen 3).

3. The unconditional and unilateral Abrahamic Covenant where God's promises Abraham that "in you all the families of the earth will be blessed" (Gen 12:1-3), the dimensions of the Promised Land (Gen 15:1-21), and "kings will come from you" (Gen 17:1-8).

4. The Exodus, which demonstrated that the invisible God was a real and existing Being.

5. The Mosaic Law, which taught one how to be holy and gain entrance into the Land:

a. How to atone for sin

b. How to avoid sin by living a righteous holy life

6. The Promised Land will be possessed after the children of Abraham "obey with all their heart and soul," are regathered from "the ends of earth" and "brought into the Land," and their hearts and those of their descendants are "circumcised" (Deut 30:2-6).

When God states, "if you will indeed obey My voice and keep My covenant, then you shall be My own possession among all the peoples, for all the earth is Mine; and you shall be to Me a kingdom of priests and a holy nation," there is an expectation that genuine Believers will know and understand the Pentateuch / Torah just as a priest should. Indeed the Levitical priesthood learned of the Law at the same time as the whole nation.

Knowing the Pentateuch / Torah well enough to teach the next generation is often repeated:

"See, I have taught you statutes and judgments just as the Lord my God commanded me, that you are to do these things in the land where you are entering to take possession of it. So keep and do them, for that is your wisdom and your understanding in the sight of the peoples who will hear all these statutes and say, 'Surely this great nation is a wise and understanding people.' For what great nation is there that has a god so near to it as is the Lord our God whenever we call on Him? Or what great nation is there that has statutes and judgments as righteous as this whole Law which I am setting before you today?

"Only be careful for yourself and watch over your soul diligently, so that you do not forget the things which your eyes have seen and they do not depart from your heart all the days of your life; but make them known to your sons and your grandsons. Remember the day you stood before the Lord your God at Horeb, when the Lord said to me, 'Assemble the people to Me, that I may have them hear My words so that they may learn to fear Me all the days that they live on the earth, and that they may teach their children.' You came forward and stood at the foot of the mountain, and the mountain was burning with fire to the heart of the heavens: darkness, cloud, and thick gloom. Then the Lord spoke to you from the midst of the fire; you heard the sound of words, but you saw no form—there was only a voice. So He declared to you His covenant which He commanded you to perform, that is, the Ten Commandments; and He wrote them on two tablets of stone. The Lord commanded me at that time to teach you statutes and judgments, so that you would perform them in the land where you are going over to take possession of it. (Deut 4:5-14)

The famous prophet Eli failed at teaching his sons, and he was judged for his failure.

For I have told him that I am about to judge his house forever for the iniquity which he knew, because his sons brought a curse on themselves and he did not rebuke them. Therefore I have sworn to the house of Eli that the iniquity of Eli's house shall not be atoned for by sacrifice or offering forever." (1 Sam 3:13-14)

There are contemporary commentators who do not think the Old Testament, specifically the Law of Moses, as being relevant and necessary to teach / exegete. The Law's stipulations on food are an example of reasons not to (Col 2:16-17), and on first glance, it may appear that the Law is obsolete:

For Christ is the end of the Law for righteousness to everyone who believes. (Rom 10:4)

So if perfection was through the Levitical priesthood (for on the basis of it the people received the Law), what further need was there for another priest to arise according to the order of Melchizedek, and not be designated according to the order of Aaron? For when the priesthood is changed, of necessity there takes place a change of law also. (Heb 7:11-12)

When He said, "A new covenant," He has made the first obsolete. But whatever is becoming obsolete and growing old is about to disappear. (Heb 8:13)

However, God intended the Mosaic Law to teach His people how to be holy and, through obedience, enter the Promised Land. From its inception, the Law was intended for the good of His people.

And now, Israel, what does the Lord your God require of you, but to fear the Lord your God, to walk in all His ways and love Him, and to serve the Lord your God with all your heart and with all your soul, and to keep the Lord's commandments and His statutes which I am commanding you today for your good? (Deut 10:12-13)

The Law taught two aspects of being holy:

1. The Law taught what sin was, which the apostle Paul recognized.

Now we know that whatever the Law says, it speaks to those who are under the Law, so that every mouth may be closed and all the world may become accountable to God; because by the works of the Law none of mankind will be justified in His sight; for through the Law comes knowledge of sin. (Rom 3:19-20)

What shall we say then? Is the Law sin? Far from it! On the contrary, I would not have come to know sin except through the Law; for I would not have known about coveting if the Law had not said, "You shall not covet." But sin, taking an opportunity through the commandment, produced in me coveting of every kind; for apart from the Law sin is dead. I was once alive apart from the Law; but when the commandment came, sin came to life, and I died; and this commandment, which was to result in life, proved to result in death for me; for sin, taking an opportunity through the commandment, deceived me, and through it, killed me. So then, the Law is holy, and the commandment is holy and righteous and good. Therefore did that which is good become a cause of death for me? Far from it! Rather it was sin, in order that it might be shown to be sin by bringing about my death through that which is good, so that through the commandment sin would become utterly sinful. (Rom 7:7-13)

2. The Law's stipulations on sacrifices taught one that sin incurred a judicial price and how to atone for it. It is this aspect of the Law that Jesus Christ fulfilled.

"Do not presume that I came to abolish the Law or the Prophets; I did not come to abolish, but to fulfill. For truly I say to you, until heaven and earth pass away, not the smallest letter or stroke of a letter shall pass from the Law, until all is accomplished!" (Matt 5:17-18)

If I had not come and spoken to them, they would not have sin; but now they have no excuse for their sin. The one who hates Me hates My Father also. If I had not done among them the works which no one else did, they would not have sin; but now they have both seen and hated Me and My Father as well. But this has happened so that the word that is written in their Law will be fulfilled: 'They hated Me for no reason.' (John 15:22-25)

Now He said to them, "These are My words which I spoke to you while I was still with you, that all the things that are written about Me in the Law of Moses and the Prophets and the Psalms must be fulfilled." Then He opened their minds to understand the Scriptures, and He said to them, "So it is written, that the Christ would suffer and rise from the dead on the third day, and that repentance for forgiveness of sins would be proclaimed in His name to all the nations, beginning from Jerusalem. (Luke 24:44-47)

God's intent of teaching two aspects of being holy through the Law has been often overlooked and misunderstood. By recognizing how the Law teaches one about sin and the judicial price for it, one can understand how the Law leads one to Jesus Christ. But because the Mosaic Covenant comprises a large portion of the Pentateuch / Torah, many do not spend much time studying the first 5 books.

Why the Law then? It was added on account of the violations, having been ordered through angels at the hand of a mediator, until the Seed would come to whom the promise had been made. Now a mediator is not for one party only; but God is only one. Is the Law then contrary to the promises of God? Far from it! For if a law had been given that was able to impart life, then righteousness would indeed have been based on law. But the Scripture has confined everyone under sin, so that the promise by faith in Jesus Christ might be given to those who believe.

But before faith came, we were kept in custody under the Law, being confined for the faith that was destined to be revealed. Therefore the Law has become our guardian to lead us to Christ, so that we may be justified by faith. (Gal 3:19-24)

Bible study should not be limited to the New Testament for without the Old Testament, one could not make sense of the New. Not only does Jesus Christ pays the judicial price and atones for the sins of mankind in fulfilling the Mosaic Covenant, He also fulfills the Abrahamic Covenant by ending sin / death (Dan 9:24; Rev 19:11-21; 20:7-15), regathers Believers from the ends of earth (Matt 24:29-31; Mark 13:24-27; Rev 14:14-16) with their hearts circumcised (1 Cor 15:50-53; 1 Thes 4:16-17) and brings them to the Promised Land (Rev 21:10-27; 22:1-5).

As a cautionary note, God has in the past judged His people by rejecting them from being His priest, because they rejected and forgot the Pentateuch / Torah.

My people are destroyed for lack of knowledge.
Since you have rejected knowledge,
I also will reject you from being My priest.
Since you have forgotten the Law (tôrâ) of your God,
I also will forget your children. (Hos 4:6)