Even so you also outwardly appear righteous to men, but inside you are full of hypocrisy and lawlessness. (Matthew 23:28)
What do those who know you the best think about you? What does God think about you? Do you find yourself constantly having to find new friends because the better people get to know you the less they think of you?
There is nothing sadder or more wearisome than trying to live a life that is a lie. An outward appearance of righteousness is temporal at best. Sooner or later the real character will be exposed. With God, it is always sooner. He knows our true character. We can never fool our Creator.
The better we become at living a lie the more apt we are to believe our own lie. Our hypocrisy and lawlessness will sear our minds and hearts to the point of being oblivious to our true character. For this reason we must continually examine ourselves. There is no greater fool than the fool who fools himself.