Job 25:4 How then can man be justified with God? or how can he be clean that is born of a woman?
Bildad’s final reply ignored Job’s examples of the prosperity of the wicked. Instead of attempting to refute Job, Bildad accused Job of pride because he was claiming that his suffering was not the result of sin. Job never claimed to be without sin, but only that his sin could not have caused his present trouble.
in the middle of his accusations, Bildad speaks a truth with a question that cannot be answered before Christ came. The truth is that no one can be justified with God by himself. And no human being can be clean or make himself clean from sin. However, the NT believer knows the answer to that impossible question: a sinful human being is justified by faith in Jesus Christ alone, and he believes that the blood of Christ cleanses from all sin.
Bildad asked the question presuming there was no answer, but we know that Christ is the answer. And we respond with faith in Christ, and we are justified and cleansed. The OT believer had to trust in the mercy of God which would in love send the Savior Messiah, but he could not yet know who that would be.