Williams says, "Job presents to us the discovery of the worthlessness of self, which should be the first step in the Christian experience.
"Job does not symbolize an unconverted, but rather a converted man. It was necessary that one of God's children should be chosen for this trial; for the subject of the Book is not the conversion of the sinner, but rather the consecration of the Saint. It is evident that an unconverted man needs to be brought to the end of himself; but that a man who feared God, who was perfect, and who hated evil, should also need this, is not so clear; nevertheless, it is a Scriptural fact."
Williams went on to say, "The effect of the Divine action was that Job abhorred himself (Job 42:5-6). The terminology used by Job shows that he had previously thought well of himself. But the sharp trials through which Job went, and especially the anger which the unjust accusations of his friends stirred up in his heart, revealed to himself unknown depths of moral ugliness; and, finally, his being challenged to measure himself up beside the Lord, made him conscious that in him, that is, in his 'flesh,' there dwelt no good thing."
JSM Bible Commentary Job