Leviticus 21 What does it mean to be holy in an unholy world? It means that we stand apart from that which is profane. It means that we see ourselves as saved by His grace and cleansed by the blood of Jesus Christ. It means we are to ask ourselves if we are partnering with those who do not believe. It means we are to come out from among them and be pure, which seems like a strict order as we move and live in a godless society, but so did Abraham, Joseph, Moses, Esther, Ruth, and Jesus.
So back to our question: what does it mean to be holy? It means that we are to remember that we are part of the priesthood of believers only because of the gift of salvation through the shed blood of Jesus Christ. It means what God gave Aaron and the High Priest as a standard applies to us in our present age. We do it when we present Christ as His ambassadors and implore them to be reconciled to God in the same way we were. It means that we mirror Christ in our walk and talk, and we can only do that when we know God. We know His character, His motives for our holiness, His standards of purity and righteousness.
God has said over and over: you should be holy because I am holy. You are my people, and thus you stand before an unholy world. The question before us is; are we a holy separated people? Only through Jesus can we have the missing puzzle pieces of purity, righteousness, and honor.