John Nelson Darby emphasizes the stark contrast between the law and the promise in Galatians 3, illustrating that the law brings a curse while the promise offers grace and blessing. He explains that the law, which demands human obedience, cannot provide righteousness or life, whereas the promise, given to Abraham and fulfilled in Christ, is based on faith and God's grace. Darby argues that the coexistence of law and promise is impossible, as they represent two distinct systems of God's dealing with humanity. He highlights that righteousness comes through faith in Christ, who bore the curse of the law, allowing believers to receive the blessings of the promise. Ultimately, Darby calls for a clear understanding of our relationship with God, which is rooted in grace rather than obligation to the law.