We can deceive ourselves into justifying our sin, but we can't deceive God. He knows what's in our hearts. And He know whether or not it lines up to His definition of right and wrong. His opinion is the only one that matters.
There have been two "Christian famous" people who have renounced their faith over the past couple of days. It's extremely sad. There was an article written by the lead singer of Skillet that I thought was interesting and relevant to today's passage (it's a bit long, but good)
Tomorrow's Bible In a Year Passage: Nehemiah 12:27-13:31, 1 Corinthians 11:1-16, Psalm 35:1-16, Proverbs 21:17-18