How do we know humans are totally depraved?

Total depravity asserts that every aspect of humanity is affected by sin; there is no part that remains untainted. The Scriptures clearly depict mankind as spiritually dead and completely sinful. Jeremiah 17:9 states that the heart is deceitful above all things and desperately wicked. Furthermore, Romans 5:12 tells us, 'in Adam all die,' highlighting that all of humanity shares in this fallen state, fashioned in rebellion against God's design. Thus, recognizing our total depravity is essential to understanding our need for divine grace.