Read Luke 16-18
And he said unto them, Ye are they which justify yourselves before men; but God knoweth your hearts: for that which is highly esteemed among men is abomination in the sight of God. Luke 16:15
There have been times that each one of us has put on a really good show for other people. We may not feel like saying or doing something, but we do just because it seems right at the time, or because it's what we know people want to hear.
The problem with this line of thinking is that God knows the motives behind our every thought and our every action. He knows exactly why we've chosen to do that or say that. We may think we can fool people, but we can't fool God.
We all know people who are fake - you can see that their actions and words don't mesh. These are the people who aren't comfortable in their own skin or are trying to avoid facing God with their real issues.
This, Scripture says, is evil in the sight of the Lord. Things that have become trivial and mundane here on earth, like faking it, wound the Lord deeply. As servants of the King we need to be honest and truthful about the reasons why we do what we do and say what we say.