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, a person is not by nature inclined to love God with his heart or mind or strength, rather all are inclined to serve their own interests over those of their neighbor. Put another way, even with all circumstances in his favor a man without God 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.

John Wesley affirmed the notion of human depravity, believing that sin utterly corrupted human moral nature, rendering man incapable of moving toward God or salvation. Wesley offered as a companion doctrine, however, the idea of prevenient grace, by which God enables humans—in spite of their depravity—to respond to Christ. It is, in effect, God making the initial move in salvation, empowering humankind to respond. Christians who are part of the Methodist family have affirmed Wesley's ideas. Many Calvinists have been uncomfortable with the notion of prevenient grace, claiming that it may be a modified version of Pelagianism, an ancient heresy which declared that humans were capable of making the first steps toward God. Wesley and his followers have defended their position by continuing to affirm the total depravity of humanity, unlike those who have adhered to Pelagian thought.

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.

See also: Free will and the problem of evil, immaculate conception, original sin, Prevenient Grace.