Leviticus deals with ritual and moral holiness. But what does that mean?
In a sociological sense, "ritual" is a process for insuring certain patterns and ideas, even meanings, for a community.
For example, saying the Pledge of Allegiance in the U.S. encourages individuals to behave in a collective fashion, which emphasizes the importance of the collective over the individual. It also affirms values that are central to this national culture: liberty, justice, and freedom, and all as "ordained by God."
We should attempt to interpret the passage from Leviticus in a similar way.
Leviticus 19:2, for example, states, "You shall be holy, for I the LORD your God am holy." (In the Hebrew, "LORD" = Yahweh, the political god of Israel/Judah.)