How do we know that original sin affects everyone?

The doctrine of original sin teaches that all humans inherit a sinful nature due to Adam's transgression. Romans 3:23 affirms that all have sinned and are in need of a savior. This concept is foundational in understanding humanity's fallen state and the necessity of redemption through Christ. Every individual, regardless of age, is born with a nature that is marred by sin and thus stands in need of God's grace and salvation. This underscores the importance of the gospel message being preached to all, including children.