Why is the concept of man as a representative important in Christianity?

The historic Reformed view emphasizes that Adam, as the first man, was a representative for all humanity. His disobedience brought sin and death to all that he represented, as stated in Romans 5. In contrast, Christ, the second Adam, lives, dies, and resurrects as a representative for His people, granting them righteousness through faith in His finished work. Understanding this representative nature clarifies the imputation of both sin and righteousness, making it foundational to sovereign grace theology.