Let’s consider the old covenant for a moment.

So if the priesthood of Levi, on which the law of Moses was based, could have achieved the perfection God intended, why did God then need to establish a different priesthood, with a new type of Priest who was in the order of Melchizedek, instead of the order of Levi and Aaron?
The fact is that the priesthood was changed for the new covenant, and so the law had to also be changed to permit it. For this new type of Priest we are talking about belongs to an entirely different tribe, of Judah rather than Levi, whose members have never before served at the altar as priests.
In spite of being spiritual and good then, it must be noted that the mosaic law never actually made anything perfect; but the GREAT news is that now we can have a confidence in a better hope, through whom we can draw near to God the Father, by the one time sacrifice His Son made on our behalf.

There are people (like the Jews) who are so proud of knowing all about the law of Moses, but yet they can’t help but dishonour God by breaking it, because it is impossible for a fallen human being to ever keep perfectly. But the real point here is that in God’s eyes a ‘true’ Jew is one whose heart is right with Him, which is mediated by the sacrifice at the cross, as the righteousness of Jesus (who kept the law perfectly) is transmuted onto those who place their faith in Him. In other words, TRUE circumcision is not so much obeying the letter of the law and physically cutting a foreskin; rather, it looks like a change of heart produced by the Spirit in someone, the spiritual ‘cutting away’ of one’s sinful nature. 
Such a person with this kind of changed heart naturally then seeks praise from God, and not from people. Yes, the law applies to those to whom it was given, for its purpose all along was to keep people from having excuses about their evil, and to show the entire world that it’s guilty before God’s judgement. Can any of us boast, then, that we have done anything worthy enough to be accepted by Him on our own merits? No, of course not, because our acquittal is not based nor has ever been based on obeying the law. Instead it is based solely on faith, just as Abraham’s own relationship with the Lord proves to us.
So, we’ve established that we are made right with God through faith and NOT by obeying the law of Moses. Well then, if we emphasise faith like this, does this mean that we can totally forget about the law? Of course not! In fact, it’s only when we have faith that we truly fulfil the law! For faith without works is a dead faith.

Let’s backtrack a little. As believers, we died and were buried with Christ, symbolised by our water baptism. Since we have been united with Him in His death, we will also be raised to life as He was. Right? So therefore, sin is no longer our powerful master, for we no longer live under the requirements of the law (the purpose of which was to expose our sin, like a schoolmaster), but instead we live under the blessed freedom of God’s incredible grace, all by His Spirit’s direct leading in our lives towards eternal life.
Well then, since God’s grace has set us free from the law of Moses, does that mean we can continue to go on sinning if we feel like it? Of course it doesn’t mean that! Since we have died to sin, how can we possibly continue to live in it? When we were joined with Christ Jesus in baptism, you should know that we joined Him in His death, for we died to the power of the law (condemnation on those who can’t keep it) when we died with Him. But remember that now in this new covenant, we are also united with the One who was raised from the dead! And the result of that amazing truth is that we can produce a harvest of faithful, good deeds for God, BECAUSE we have been released from the law, having died to it and are no longer being captive to its power. For the law inadvertently gave sin its dreadful power over us all, through ‘tickling the flesh’; yet now we can truly serve God, not in the old way of obeying the letter of the law, but in this new way of living in the Spirit!

Because of this limiting, impossible ideal it required of us as fallen, imperfect human beings, resulting in our condemnation, am I then suggesting that the law of God is in any way sinful? Of course I’m not! In fact, it’s wonderful that the law that shows us our sin, for we then see our desperate need for the Saviour. An example of how it worked was that we would never have known that coveting is wrong if the law had not said, “You must not covet”, but sin uses commands like this to arouse all kinds of wicked desires within us! If there were no laws to keep, sin would not have that power. So you can see just from that example how wicked sin really is!
Let’s be clear that the law itself is holy, and its commands are holy and right and good. And we know that the law is good when it’s used correctly, for the law was not intended for people who do what is right, it’s actually for people who are lawless and rebellious, who are ungodly and sinful, who consider nothing sacred and defile what is holy. Did the law, which we’ve already noted is good, directly cause our deaths then (as the wages of our sin that was pointed out by and condemned by the law)? A resounding ‘no’ to that question too! As I’ve explained already, what happened was that sin used what was good to bring about our condemnation unto death. So we can again see just how terrible sin really is! It uses God’s good commands for its own evil purposes. It is obvious to those who know His Spirit that the sinful nature is and has always been hostile to God… it never did obey God’s laws, and it never will, and this is the fruit of being in agreement with the flesh rather than following the Spirit. 
So then, it must here be noted that we are still sinning if we try to rebuild the old system of law that was already torn down, for if we ever try to keep the law for righteousness’s sake, it always condemns us, for sin gets its power from it. As we know, everyone who sins is breaking God’s law, for sin is what’s contrary to the law of God. Remember, the person who keeps all of the laws except one is as guilty as a person who has broken all of God’s laws! So, the point here is that trying to keep the law of Moses in order to produce righteousness always ends in condemnation, which is why the Lord changed the covenant entirely, so that we attain HIS righteousness through no work of our own, and reconcile with the Father by the blood of Christ.

So, we need to remember that we’ve died to the whole law, in Christ and with Christ. We have to stop trying to meet all its requirements for their own sake, so that we might instead live for God through the direct indwelling guidance of His Spirit, and allow HIM to produce His own fruit in and through us. The fruit comes with abiding in Him, not in keeping the law. Those who now depend on the law to make them right with God are actually under His curse, for the Scriptures say, “Cursed is everyone who does not observe and obey all the commands that are written in God’s Book of the Law.” And let me tell you, it’s true! If you are trying to make yourselves right with God by keeping the law, you have terrifyingly been cut off from Christ! You have fallen away from God’s grace… but when you are directed directly by the Spirit, you are no longer under obligation to the law of Moses, for this is the new way of producing faithful works that have eternal merit, and is the only way to personally meet with God, having been redeemed unto holiness.
Let me put it this way: the old law was humanity’s guardian until Christ came; it protected people until the time came where we could be made right with God, through faith in the atoning sacrifice. Now, it’s Christ Himself who has brought peace to us! He has united Jews and Gentiles into one people when, in His own body on the cross, He broke down the wall of hostility that separated us. He did this by ending the old system of law, with all its commandments and regulations. He made peace between Jews and Gentiles by creating in Himself one new people from the two groups. Together as one body, Christ reconciled both groups to God by means of His death on the cross, and our hostility toward each other was put to death.

Once more, to be clear: we should no longer count on our own righteousness through obeying the law; rather, we become righteous through faith in Christ, who produces the works in us that HE wants to produce (and therefore takes the credit for them). For God’s way of making us right with Himself depends on faith. And as a cherry on top, He has now enabled us to also be ministers of this new covenant to others. This is a covenant not of written laws, but it’s of the Spirit. The old written covenant ends in death; but under the new covenant, the Spirit gives eternal life. Since we are now living by the Spirit then, let us follow the Spirit’s leading in every part of our lives!