Why do believers observe the Day of Atonement if Yeshua already made atonement?

This Teaching approaches the Day of Atonement as a study of access to Yehovah’s presence. It begins by stating that observing the appointed day does not repeat or supplement Yeshua’s sacrifice; rather, Leviticus 16 provides a pattern through which sin, atonement, cleansing, mediation, priesthood, and access to the holy presence can be understood. The account of Nadab and Abihu in Leviticus 10 becomes an important starting point. Their unauthorized approach is used to emphasize the words, ‘By those who come near Me I must be regarded as holy,’ and the Teaching develops the theme that fallen humanity cannot approach Yehovah on its own terms. The boundaries, washing, clothing, blood, incense, and mediation surrounding the high priest are presented as purposeful provisions for approaching the holy presence and living. The Teaching then turns to Yeshua. Hebrews 9 is used to show that Messiah entered the greater sanctuary with His own blood and obtained eternal redemption. The speaker emphasizes that the Day of Atonement pattern did not end with the high priest entering the Most Holy Place: the people waited for him to reappear. This becomes the Teaching’s central connection to Hebrews 9:28, where Messiah appears a second time, apart from sin, for salvation to those eagerly waiting for Him. Hebrews 10 is then used to connect Yeshua’s priestly work with believers drawing near with confidence. The Teaching also asks what the Day of Atonement means after Yeshua’s return. It is careful to state that Scripture does not explicitly assign a particular prophetic event to a future Yom Kippur. Several possibilities and participant observations are discussed – including cleansing, the removal of evil influence, Israel, the millennial period, and the memorial character of the appointed time – but these are presented as matters for continued study rather than as explicit statements of Scripture. The closing discussion also considers afflicting oneself, fasting, Isaiah 58, serving others, and approaching unresolved prophetic questions with humility, faith, and trust.