The central message of this sermon is that the Mosaic Law, given to the people of Israel at Mount Sinai, serves as a measuring rod for humanity's inability to achieve moral perfection and thus necessitates redemption through a Savior. By highlighting the law's role in corraling people towards their need for salvation, the sermon advances the belief that humans are incapable of achieving perfect obedience to God's standards on their own. The takeaway is that the law's primary function is not to enable people to achieve righteousness but rather to demonstrate their inherent inability to do so, thereby pointing them towards a Savior who can bridge the gap between humanity and God's perfection. This message underscores the idea that salvation is not about human effort or achievement but rather about receiving it as a gift from a divine Redeemer.