"And the LORD spoke to Moses, saying, 'Now on the tenth day of this seventh month is the Day of Atonement. It shall be for you a time of holy convocation, and you shall afflict yourselves and present a food offering to the LORD. And you shall not do any work on that very day, for it is a Day of Atonement, to make atonement for you before the LORD your God.'" Leviticus 23:26-28
The day of Atonement was a day of national cleansing and repentance from sin. It was on this day that God judged the sins of the entire nation of Israel.
As Christians, even though God has forgiven us of our sins, this does not mean that we do not need a continuous cleansing in our daily lives. We must judge our sins daily for the purpose of maintaining fellowship with Jesus. The blood of Jesus purifies us so that we can have continuous fellowship with Him.
"If we say we have fellowship with him while we walk in darkness, we lie and do not practice the truth. But if we walk in the light, as he is in the light, we will have fellowship with one another, and the blood of Jesus His Son cleanses us from all sin. If we say we have no sin, we deceive ourselves, and the truth is not in us. If we confess our sins, he is faithful and just to forgive us our sins and to cleanse us from all unrighteousness." 1 John 1:6-9
"If my people who are called by my name humble themselves, and pray and seek my face and turn from their wicked ways, then I will hear from heaven and will forgive their sin and heal their land." 2 Chronicles 7:14
~~~
I would encourage you to check out The Return by Jonathan Cahn. "National Day of Prayer and Repentance". Check out the website: https://thereturn.org/
*Quite a bit of the information is from "Celebrating Jesus in the Biblical Feasts" by Dr. Richard Booker. Highly recommended!*