"Then Job replied: 'Indeed, I know that this is true. But how can mere mortals prove their innocence before God? Though they wished to dispute with him, they could not answer him one time out of a thousand. His wisdom is profound, his power is vast. Who has resisted him and come out unscathed?'" NIV translation
Job had listened to Bildad speak about the religious traditions of their ancestors and he does not dispute the things that have been said. His assessment of the situation is that, although the things that were said were true, they did not speak to the problem that he was facing. We are reminded of the fact that what Job was dealing with was the problem of understanding why all these bad things were happening to a good man such as himself. He wishes for someone that could compare to God in wisdom that could step in and defend him in this matter. Here, we see a fundamental error in his understanding of God as He asks who could "prove their innocence before God". The Hebrew word that is translated here as "innocence" is "tsadaq" and it means "righteous". Tsadaq comes from the root word "tsadiyq" which literally means "a straight line". For a line to be perfectly straight, there can be no deviation between the beginning and the end. With this in mind, we see that Job does not see innocence as perfection which is God's standard. Instead, he looks at it based on a comparison to those that do not know God. In effect, Job sees that he is not perfect but he is pretty good compared to the wicked (ungodly). He goes on to acknowledge the fact that no man has the wisdom to match God but he still has questions that he wants answered. This same type of thing is widespread in our world today (even among Christians). We often lose sight of the fact that, on our own, not a single one of us is righteous (innocent) before God. This comparison of our lives with others in relation to God instead of comparing ourselves to His standard is commonly called relativism and is a favorite tool that the devil uses to deceive people.