The Laws of Moses actually put the nation of Israel under a curse if they did not obey all 613 laws. So what was the purpose of the law? It was to show us how fallen we are and have us turn to God in faith that He would provide a way. That way was not the animal sacrifices, for God says He was never pleased with them. They only pointed forward to the sacrifice He would provide. The righteous are not those who try to keep the laws, but those who live by faith in His Word, just as Abraham who believed in God's promise to Him.