Sometimes there are doubts about Adam being a representative for all. The point here is to emphasize the fact that Adam was a Federal Head. That is to say that Adam represented not just himself but all mankind. This sometimes comes under attack by the likes of Pelagians and others who will usually end up in a heresy of some sort (pick your heresy). The Doctrine of Original Sin in summary is that we have inherited the sin and guilt from Adam’s sin in The Fall to our present state now. We are therefore born in sin and live our life struggling with our sinful nature.
That is why we don’t need help sinning but we do need to know about salvation, sanctification and how we ought to persevere in the faith. These are things that are alien to man and not naturally something we can do on our own.
This sinful state is generally referred to as a state of spiritual death. We are born dead in our sins means that we are born dead spiritually.
“And you were dead in the trespasses and sins”
(Ephesians 2:1 ESV)
But the amazing part is when God makes us alive by His own strength for His own glory.
“even when we were dead in our trespasses, made us alive together with Christ—by grace you have been saved—”
(Ephesians 2:5 ESV)
Celebrate life in Christ. The dead man is gone. Your sinful flesh of Adam is dead and your life is now in Christ.