In Romans 5:12-21, Paul explains how sin entered the world through our representative Adam, leading to death for all humanity. He contrasts Adam’s disobedience with Christ’s obedience. While sin and death spread through one man’s failure, God’s grace and the gift of righteousness come through Jesus. Paul emphasizes that just as death reigned through Adam, grace reigns through Christ, offering eternal life to those who believe. Paul points out that all in Christ are saved, and all in Adam are condemned. This is not a universal salvation but a consolation that Christ’s work overcomes Adam’s fall for all who are in Christ Jesus.