What is total depravity and why does it matter?

Total depravity, a core tenet of Reformed theology, asserts that due to Adam's sin, all humans inherit a sinful nature. Scriptures like Romans 5:12 affirm that 'as by one man sin entered into the world,' which signifies our complete inability to attain righteousness on our own. Understanding total depravity emphasizes the necessity for God's grace and salvation. It matters because it highlights that without divine intervention, mankind remains in spiritual death, further magnifying the glory of God's grace in effectual redemption.