While Leviticus makes for difficult reading for people today, it contains a simple message that everyone needs to learn: God is holy, so we may approach him only in the manner he determines. In the context of Leviticus, God determined that his people approach him through a holy priest offering a perfect sacrifice.  However, the fact that the people had to offer many sacrifices through many priests over many centuries indicated that none of the sacrifices finally took away their sins.  It turns out that the whole system was pointing forward to Jesus, the only truly holy priest who offered himself as the only perfect sacrifice.