The third chapter in this book is about the fall of man. Plantinga talks about many things involving predestination. The quote "sin has become a habit in man," seems to make it sound as if sin has been progressively getting worse over time, when really it has been just as bad all along. He states that sin interferes with the way that God wants things to be, almost as if sin was not expected by God? I believe in predestination and that God has all things in His plan even as they are today.
Everything that is going on today is in accordance with God's plan and there is nothing that surprises or happens out of plan. Plantinga also seems to deny the total depravity of man. Adam and Eve are our first parents and because of them being our great grandparents we are then responsible for the fall and are then totally depraved. "And the Lord said in his heart, I will not again curse the ground any more for man's sake; for the imagination of man's heart is evil from his youth." (Gen 8:21)