Total depravity is a theological term primarily associated with Calvinism, which interprets the Bible to teach that, as a consequence of the Fall of man, every person born into the world is enslaved to the service of sin. In other words, each person has a natural inclination not to love God with his heart or mind or strength; and every person is inclined to serve his own interests over those of his neighbor. Or, put yet another way, man without God, even with all circumstances in his favor, can do nothing but work for his own destruction; and even his religion and philanthropy are destructive, to the extent that these originate from his own imagination, passions and will.
"Total depravity" does not mean that all men are as bad as possible. Rather, it means that even the good which men intend is faulty in its premise, false in its motive, and weak in its implementation; and there is no refinement of his natural capacities that can finally correct this condition. In the Calvinist system, the logical corollary is that salvation is only possible because of the grace and mercy of God, and is not owing to human work (Sola gratia). Although it is easily confused with philosophical cynicism, total depravity counsels optimism concerning God's love for what He has made, and His ability to accomplish the irreproachable good that He intends for his creation, even through the agency of sinful human beings.
This understanding of human depravity is comparable in almost every respect to Martin Luther's view of man's state after the Fall. Lutheranism and Calvinism both appeal to Augustine of Hippo for their understanding of Original sin. Of course, there are many Christian groups, also among Catholics and Protestants, including in the Lutheran churches and the Reformed churches, that disagree with this interpretation of both the Bible and of Augustine. This understanding of human depravity was also not shared by Augustine's contemporaries in the Greek-speaking part of the church, and is still not shared in Eastern Orthodoxy.