I believe that people are offended because it shows them and others that they are not who they pretend to be. Also, people like to think that the wrong things that they are doing is not all that bad. As I understand the Bible there is no difference between sins, sin is sin. So when we read the Bible which is our mirror is shows us our true self; and sometimes we don't like what we see, so we will deny that we are all that bad, but our sin stinks in the nostrils of God.