Total depravity is a term that is used to summarize what many Christian theologians and leaders have traditionally taught about the spiritual condition of sinful and fallen man. The term "total depravity" does not mean that an individual necessarily commits all the sin he is capable of, but merely that man's core nature (mind, will, emotions) have been corrupted by sin and is incapable of attaining righteousness and salvation without God's regeneration. Although the doctrine of "total depravity"/"depravity of man" is commonly associated with Calvinism, it is not exclusively a Calvinist doctrine. For example, John Wesley the founder of Methodism, was not a Calvinist and he had extremely similar ideas concerning the depravity of man as John Calvin.
This doctrine is supported by Bible verses such as the following:
Jeremiah 17:9 - "The heart is deceitful above all things, and desperately wicked; who can know it?"
John 3:19 - "This is the verdict: Light has come into the world, but people loved darkness instead of light because their deeds were evil."
Romans 3:10-12 - "As it is written: 'There is no one righteous, not even one; 11there is no one who understands; there is no one who seeks God. 12All have turned away, they have together become worthless; there is no one who does good, not even one.' "