I think one of the things about the Christian life is the struggle between being holy and yet not inadvertently sending out the message of being holier-than-thou.
The term being holy doesn't seem to be one that is common in our everyday language.
Yet that is part of the identity of a Christian. We are chosen, holy and dearly loved by God. But somehow we don't behave as if we were. Being holy means we are special in the eyes of God.
Do we believe we are special? It doesn't mean we are better than our fellow man. Its not that we are cleverer or more beautiful than others. But it's just the realization that our position is different in the eyes of God. And because of that, we should walk with our heads straight, not down.
Because of our position, we should behave in ways that befit it. How would we expect the King of England to behave? How should we expect an ambassador to behave?
Imagine a prince or emperor goes out to visit and mingle with his people. But he is in disguise. He comes out in disguise, sometimes as a beggar, sometimes as an engineer, sometimes a teacher. In this disguise, he is sometimes respected, but often times looked down and insulted. Yet does the treatment he gets while in disguise entitle him to behave unroyally? No, while he has not revealed his true identity he must maintain his dignity. No matter the situation he is put in, as long as he remembers his identity he can maintain an attitude of self-respect and servanthood.
Being holier than thou is a form of pride. But we must remember that our fellow man is also a fellow prince, the only thing is that he too may not realize it or refuses to acknowledge his identity. You may as well be proud that you are human.
But back to holiness. Realizing that we are holy allows us to even do menial things with dignity. It gives us also authority to rebuke (or overlook) insults. The more we realize our identity, the more we will change our behaviour.
It is because we are holy that we do not engage in impure behaviour, actions, thoughts or speech. It is because we are holy that we have esteem. It is because we are holy that we can do the simplest task with dignity or achieve great things with confidence.