Excerpt from GotQuestions.org
However, even when the doctrine of total depravity is properly understood, many people will reject the doctrine, but that fact should not surprise us, since the world generally thinks of man as being basically good. Therefore, the idea that man by nature is a depraved sinner runs contrary to most modern religious, psychological and philosophical views of the basic nature of man. But the fact is that the Bible does teach the depravity of the human heart, and the root cause of man’s problem is not the environment he is raised in but his wicked and selfish heart. Properly understood, the doctrine of total depravity will destroy the hopes of those who place their faith in any type of works-based system of salvation and will recognize that God’s sovereign grace is man’s only hope. While the doctrine of total depravity destroys man’s self-righteousness and any misconceptions about man’s ability to be saved through his own free will, it leaves one asking the same question the disciples asked of Jesus in Matthew 19:25-26: “Then who can be saved?” Of course the answer remains the same: “With people this is impossible, but with God all things are possible” (Matthew 19:25-26).
As the first of the five doctrines of what is called “Calvinism,” the doctrine of total depravity correctly focuses man’s attention on the rest of these “doctrines of grace” which declare the wondrous work of God in the salvation of sinners.