The brevity of this speech reflects the fact that Job's companions were running out of arguments. Job's responses were at least silencing them if not convincing them.
Bildad seems to have abandoned the earlier theme of the wicked's fate because of what Job had just pointed out. Instead he merely emphasized the sinfulness and insignificance of all people and God's greatness. Perhaps he hoped Job would admit to being a sinner since the whole human race is unclean. He felt Job was absurd in thinking that he could argue before God.
Verse 4 restates a basic question that had come up earlier in the debate (4:17; 9:2b; 15:14). The answer did not come in this book, but it came later with subsequent good news of God's grace. Perhaps Bildad raised it here to convince Job that neither he nor anyone else could be as guiltless as Job claimed to be. The illustrations that follow in verses 5-6 support his point.
Interestingly this last statement, the last of all those recorded in the book that Job's three friends uttered, is a very depressing one. These men had come to comfort Job, but their words and world view made that impossible.
