In the Hebrew Bible (TANACH), Yom Kippur is called 'Yom Hakippurim' - literally ‘The Day of Atonements or Coverings’ (Leviticus 23:27-32). It is the only day for which the Lord commanded His people to fast. It is another opportunity to return to God and obey the instructions of God.
During the Temple period, the focus of ‘Yom Hakippurim' was to cleanse the Sanctuary from the people’s sins and the contamination accumulated there by means of the substitute animals that were sacrificed. This contamination was taken away by the Azazel (the scapegoat) to the wilderness. “Behold! The Lamb of God, taking away the sin of the world! (John 1:29). This is the day we come to God to be reconciled with Him through Jesus, Mediator and Sacrifice (Kaphar). Because of Messiah, our names can be inscribed in the Book of Life.