Douglas Wilson
Blog&Mablog
INTRODUCTION
It may seem odd to put it this way, but the only thing that can save us from the sexual revolution now is total depravity. Of course this is shorthand, but it is shorthand with a point.

Of course we know that it is Christ who saves us, and total depravity is not the name of our Savior, but rather a phrase that refers to what we are saved from. Hence the shorthand.
And it is not the most ideal phrase either. It makes people think that we are proclaiming something like absolute depravity, which sounds like we are saying the unsaved are orcs out of hell, already as bad as it is possible for a creature to get, with no common grace whatever. Yeah, that’s not accurate either.
But let’s just go with total depravity for a bit. Work with me here.
HORSE DOSES OF CALVINISM
In theology, there are two foundational approaches to human nature out there, and they are the Augustinian and the Pelagian. Calvinism is simply a later nickname given to the Augustinian approach.
According to the Augustinian understanding, moral obligation is created by the Word of God. Morality is defined by the law of God. If Scripture says not to do something, then doing it is sin. Pretty straightforward.
But according to the Pelagian understanding, moral obligation is defined by our abilities. Put another way, there is no moral responsibility that can be assigned to inability. According to Pelagianism, sin is not sin unless it can actually be avoided. Sin is always a function of free choice, and hence cannot be grounded in our nature. There is no such thing as a constitutional or natural depravity.
The Augustinian answer to this, of course, is a raft of Bible verses.