How do we know that humans are born sinners?

The doctrine of original sin asserts that through Adam's disobedience, sin entered the world and infected all humanity. Romans 5:12 states that by one man, sin entered into the world, and as a result, all have sinned. This indicates that every human being is born with a sin nature, unable to please God without divine intervention. The fall did not merely wound humanity; it resulted in spiritual death, rendering us incapable of righteousness on our own. Ephesians 2 highlights this condition, describing us as dead in our trespasses and sins and under the influence of the prince of the power of the air, emphasizing the complete inability of man to seek God without His grace.