Total depravity teaches that the fallenness of our condition affects the radix, the core of our being. It’s a radical thing. There is no part of our humanity that has not been profoundly affected by the fall and by sin. The mind, the heart, the will, the body—the whole person, in totality, has been radically affected by sin. But that affectation does not destroy or annihilate the image of God. In Noah’s time, God instituted capital punishment for first-degree murder because the person who murders another human being does so to a human being who is made in the image …
SPROUL: In the first place, we’re talking about what we ought to do as distinguished from what we actually do. God commands us to seek after Him. God commands us to be perfect. God commands us to be obedient in all things. The assumption is that if God commands you to do something, you must have the ability to do it. This is what created the biggest theological issue in the first four centuries of Christendom—the debate between Pelagius and Augustine over the question of whether we, as fallen human beings, have the moral ability to lead perfect lives.