Total Depravity: The Hostility of Men to the Gifts of God

"Those who live according to the flesh set their minds on the things of the flesh, but those who live according to the Spirit set their minds on the things of the Spirit. For to set the mind on the flesh is death, but to set the mind on the Spirit is life and peace. For the mind that is set on the flesh is hostile to God, for it does not submit to God’s law; indeed, it cannot. Those who are in the flesh cannot please God."
- Romans 8:5-8

Paul says something that seems very clear to me: "You were dead in trespasses and sins" (Ephesians 2:1). Theologically, we refer to that as spiritual death. Since the fall of Adam, every man, woman, and child (except Jesus) has entered physical life with a dead spirit. And just as a corpse cannot bring itself back to life, neither can the dead spirit. It is only the Holy Spirit that can bring new spiritual life (John 3:6, Ezekiel 36:26-27).

However, even among professing Christians, this biblical teaching is very unpopular. There remains a part of our spirit that wants to take credit for our salvation. Therefore, while professing Paul's words here, most Christians otherwise teach that men aren't dead in sin, but merely sick. And, just as a physically-sick man can treat himself for his disease, they believe that the spiritually-sick man can cooperate with God in his own salvation.

However, as Paul says in the Romans passage quoted above, unbelievers don't feebly strive for salvation. Rather, it is their natural spiritual condition to hate God, reject His authority, and to turn away from any concept of salvation. Men aren't naturally able to be saved; they are, instead, naturally inclined to remain dead in sin!