Job denies having sinned. But even if he had sinned, why does God respond with so strong a punishment? It is not as if Job could have done anything to harm God. Again, Job is wrong to portray God as a strict watcher of men.
The truth is that God is full of kindness and forgiveness. At the end of the book, God will also declare his continued approval of his servant Job.
20 If I sin, what do I do to you, you watcher of mankind? Why have you made me your mark? Why have I become a burden to you?