The law of Moses which is God's law was given for many reasons. Mainly this one.
Search the scriptures; for in them ye think ye have eternal life: and they are they which testify of me. John 5:39
Jesus the way, the truth and the Life.
I call heaven and earth to record this day against you, that
I have set before you life and death, blessing and cursing: therefore choose life, that both thou and thy seed may live: Deut 30:19
What was set before them that day?
If thou shalt
hearken unto the voice of the LORD thy God, to keep his commandments and his statutes which are written in this book of the law, and if thou turn unto the LORD thy God with all thine heart, and with all thy soul. For
this commandment which I command thee this day, it is not hidden from thee, neither is it far off. It is not in heaven, that thou shouldest say, Who shall go up for us to heaven, and bring it unto us, that we may hear it, and do it? Neither is it beyond the sea, that thou shouldest say, Who shall go over the sea for us, and bring it unto us, that we may hear it, and do it? But the word (
this commandment, thou shall hearken unto the voice of the LORD thy God, to keep his commandments and his statutes which are written in this book of the law, and if thou turn unto the LORD thy God with all thine heart, and with all thy soul.) is very nigh unto thee, in thy mouth, and in thy heart, that thou mayest do it. See, I have set before thee this day life and good, and death and evil; In that I command thee this day to love the LORD thy God, to walk in his ways, and to keep his commandments and his statutes and his judgments, that thou mayest live and multiply: and the LORD thy God shall bless thee in the land whither thou goest to possess it.
(Deu 30:11-16 KJV)
These text are paraphrased in Romans 10.
But the righteousness which is of faith speaketh on this wise, Say not in thine heart, Who shall ascend into heaven? (that is, to bring Christ down from above
Or, Who shall descend into the deep? (that is, to bring up Christ again from the dead.) But what saith it? The word is nigh thee, even in thy mouth, and in thy heart: that is, the word of faith, which we preach;
(Rom 10:6-8 KJV)
Christ through which the word (
this commandment, thou shall hearken unto the voice of the LORD thy God, to keep his commandments and his statutes which are written in this book of the law, and if thou turn unto the LORD thy God with all thine heart, and with all thy soul.) is in the heart, mind and mouth that we may do it. that is, the word of faith, which we preach;