However, Augustine's teaching on man's will says something quite different:
"Augustine argued that there are four states, which are derived from the Scripture, that correspond to the four states of man in relation to sin: (a) able to sin, able not to sin (posse peccare, posse non peccare); (b) not able not to sin (non posse non peccare); (c) able not to sin (posse non peccare); and (d) unable to sin (non posse peccare). The first state corresponds to the state of man in innocency, before the Fall; the second the state of the natural man after the Fall; the third the state of the regenerate man; and the fourth the glorified man.
Augustine's description of the person after the fall "not able not to sin (non posse non peccare)" is what it means for humanity to have lost the liberty of the will. Fallen man's will is free from coercion yes, but not free from necessity... ie. he sins of necessity due to a corruption of nature."
Correction:
I can’t find the reference in “Mere Christianity” where he says he is not the best theologian. It may have been in one of his other works, or it could be based on a discussion I had with several other regarding the later chapters of his book. In either case, I retract that statement.
David was fallen man, but he (sometimes) chose to do God's will. All the prophets were fallen but obeyed God.
Abram had not yet been redeemed but did God's will.
How do you explain that?