As early then as the time of Isaiah we find the doctrine of the reformation of character dependent on forgiveness of sin distinctly taught.
Consider:
I. The demand made. (1) The nature of the demand. It is for a reformation of practice. Put in one word, it is Reform. This is the one Divine call to fallen man. At one time it is an old commandment, at another a new one. Whether it be faith or love, hope or patience, that are enjoined, they are all to issue in the moral elevation of man's character. (2) The word "learn" suggests a further thought, namely, the ground of this demand for reform. The ground of the demand is the perversity of the human will. (3) Consider the justice of the demand. It is God who makes it. But He could not have made it unless it were just to do so; nor would He have made it unless it were possible for man to meet it.
II. How to meet God's demand for reform. (1) The answer of nature. The belief in the ability of man to reform himself is founded either on ignorance of the real nature of his moral condition, as was the case in the pagan world, or on a deliberate refusal to recognise the truth when it is presented concerning that condition, as was the case in Judaism, and is the case at the present day with those who persuade themselves to a belief in the infinite intrinsic capability of human nature. (2) The answer of grace. A power from without is absolutely necessary to enable man to meet the demand for reform. This power is God's forgiveness. (a) Pardon is an inducement to repentance, which is the first step in the reformation of character, (b) Pardon removes, or rather is itself, as its name implies, the removal of sin. When sin itself is removed in forgiveness, all its consequences, too, will soon vanish; and lightened of our burden, we shall feel free and ready to undertake the duties of the new life.
R. E. Morris, The Welsh Pulpit of To-Day,p. 295.