Ross's sermon on Galatians 3:15-25 explores the relationship between God's promise to Abraham and the Law given through Moses, emphasizing that salvation comes by grace through faith, not by works. He explains how the law reveals our sin and points us to our need for a Savior, serving as a guide until Christ fulfilled it. Through vivid illustrations, he highlights God's unchanging promise, the law’s purpose, and the freedom found in Jesus. The message calls us to trust in Christ alone, leaving behind the burden of works-based righteousness to embrace the rest and assurance found in Him.