The third book of the Bible is so called because it describes the service
and work undertaken by the Levites; those who were of the tribe of Levi
and who stood aside from many of the sins of Israel (e.g. Exodus 32:26).
Leviticus, in summary, defines the rules and instructions that Israel had to follow for worshipping God in the correct way, and covers such subjects
as the necessity for sacrifice, thank-offerings, sin-offerings, the holiness
of God and the necessity of a mediator between God and Man. The book
therefore foreshadows much of the work of the Lord Jesus Christ and so
is relevant to believers today.