So the law of Moses was given to a stubborn and stiffnecked Israel to teach them the rhythm of obedience. It was also to teach them the meaning of the Atonement of Christ through symbols and types of things to come.
But of course this whole complicated law of Moses only had significance if the people understood its meaning. Therefore the prophet asks:
“And now, did they understand the law? I say unto you, Nay, they did not all understand the law; and this because of the hardness of their hearts; for they understood not that there could not any man be saved except it were through the redemption of God.”