Layman's TULIP: Total Depravity

The 'T' stands for Total Depravity. That's merely theological lingo for the sinful condition of man's nature due to the sin of Adam. Adam sinned in Eden. That sin caused his nature to be fallen. Because his nature was fallen, all men subsequently became fallen at birth. Or, as Paul puts it, "just as sin came into the world through one man, and death through sin, and so death spread to all men because all sinned" (Rom. v.12). And again, "as by a man came death" and "as in Adam all die" (1 Co. xv.21-22).

You say, "Wait. Arminians believe the same thing. What's the difference?" Good question! Think about the phrase: Total (complete, absolute, without lack, none excused, 100%, all) Depravity. Arminians believe that a part of the human nature did not fall with Adam. Reformed theology teaches that we completely fell. Arminians believe there is enough of this libertarian free will, by which we are judged as being liable for our sin, in each of us that we ultimately have to choose.

Look at the Scriptures:

As it is written: "None is righteous, no, not one; no one understands; no one seeks for God. All have turned aside; together they have become worthless; no one does good, not even one." (Rom iii.10-12)

even when we were dead in our trespasses (Eph 2:5)

The Westminster Confession of Faith, a major document and confession for reformed believers (but not on par with Scripture, contrary to some of the railings and attacks by "many"), says the following:

Man, by his fall into a state of sin, hath wholly lost all ability of will to any spiritual good accompanying salvation: so as, a natural man, being altogether averse from that good, and dead in sin, is not able, by his own strength, to convert himself, or to prepare himself thereunto. WCF ix.3

The idea is that man is fallen, in sin, at enmity with God, and unable to do what is good, to turn to God, by his own will because his will is enslaved by sin. Many a non-reformed believer will say, "Jesus offers salvation to every human, but each human has to stretch out his or her hand and take the gift, to accept it as his or her own." The problem is a dead person cannot stretch out their hand. Someone who hates God will not, by their own volition, simply go to God.