Though the law, given through Moses, was glorious yet it only finds out sin and brings condemnation. None can perfectly keep the law and so it cannot give life.
It was given to bring the knowledge of sin that such knowledge might turn the heart to seek the Lord for His salvation.
His salvation rests upon His promise and work and any who believe Him will be accepted as Abraham was.
Abraham did not have the Law of Moses and trusted in God’s promise and that God would provide.
And he believed in the LORD; and he counted it to him for righteousness.
His righteousness came by faith and not by law keeping or by doing "good works."
The law was given to provide a measure and restraint upon sin that by it the heart should turn to the Lord for His promises and provision which the law served to illustrate.
When Moses spoke with God in the tent of meeting his face shone with the glory and he covered his face until that glory faded away.
This illustrates the fading glory of the law next to the revelation of God, His provision received by faith and trust in Him.
... And not as Moses, which put a vail over his face, that the children of Israel could not stedfastly look to the end of that which is abolished:
But their minds were blinded: for until this day remaineth the same vail untaken away in the reading of the old testament; which vail is done away in Christ.
But even unto this day, when Moses is read, the vail is upon their heart.
Nevertheless when it shall turn to the Lord, the vail shall be taken away.
There is a blinding upon the Jews, upon their minds, largely by their own teaching and instructing each other and their pride in their own people and their blind nostalgia that they are God's special people irrespective of their sin and disobedience and rebellion. Obviously God's people should be obedient to God if they are to remain His people.
The Jews, those who try to be serious, cling to the law of Moses and their righteousness by their own works based on that law and therefore not only fail of God's standard but thereby refuse God and His revelation and the perfect righteousness that He gives by faith in what He has accomplished.
Even throughout the Scriptures, from Abraham and through the history of Israel, it has always been a remnant who are saved by faith and not just because of being born a Jew after the flesh. The latter view is itself terrible pride and superiority.
The constant sin and falling away of Israel from God to false religions ought to amply demonstrate the point. Any Jew who reads the Bible should be utterly embarrassed and ashamed of his people for their record of sin, disobedience, rebellion and falling away from the true God and alarmed for himself. It is also God witnessing to us by their example that if those He called to be His people were like that then we will all be like that unless we seek Him from the heart.
Instead the majority follow the example of their forebears and do not seek God for themselves. In that they do not follow Abraham or Moses.
If you want the witness of God then read the warning of Moses in Deuteronomy 28, especially of scattering, and consider that the Jews have been in exile and dispersion for some 2000 years and their Temple utterly destroyed.
Any religion that turns the heart from the revelation of God and from seeking Him is the worst on earth.