How do we know man is sinful according to the Bible?

Scripture depicts the fallen nature of humanity with stark clarity. In Isaiah 64:6, it is declared that all our righteousnesses are as filthy rags, portraying the utter depravity of mankind. Every person, being a descendant of Adam, is deemed a dead, vile sinner before God—helpless and without hope in themselves. Romans 3:10 reinforces this idea, stating that there is none righteous, no not one, further solidifying the biblical view that every individual is guilty of sinning against God and in need of divine intervention for salvation.