Yom Kippur (the Day of Atonement) was ordained by God to fall on the tenth of Tishri, and it is the last day of the 40 Days of Repentance - the last 10 days of which being called the Days of Awe. This Holy Day focuses on a twenty-four hour period of repentance and intense self analysis of one's life before the Lord. Appropriately, Yom Kippur preceeds the feast of Tabernacles (the season of joy), just as redemption and forgiveness preceeds joy!
A person, or a corporate group of like minded people, uses this God ordained time to seek forgiveness and to be restored to fellowship with the Maker Himself. Yom Hakippurim (the Biblical name) means "the day of covering or concealing" and is reflective of the salvation and atonement made through the death of Yeshua (Jesus) on Calvary's hill.
Erev Yom Kippur (the evening of Yom Kippur) begins at sundown and continues through sundown on Tishri 10 on the Jewish Calendar.
Once a year, the High priest took two goats. One was slain and its blood sprinkled on the mercy seat in the Tabernacle; on the other goat he laid his hands and imparted the sins of the whole house of Israel. This goat was sent out of the camp and into the desert. It was called the ‘scapegoat'.
When Yeshua, the High Priest, gave his life as an offering for us, he not only represented the Passover Lamb, but he also accomplished the duty of the High Priest on the Day of Atonement. His blood was poured out and presented before God as an atonement. Not only did he redeem Israel, but also took upon himself the sin of the world. "Surely he hath borne our griefs, and carried our sorrows....But he was wounded for our transgressions, he was bruised for our iniquities: the chastisement of our peace was upon him; and with his stripes we are healed." (Yesha'yahu - Isaiah 53:4-5). "For Christ is not entered into the holy places made with hands, which are the figures of the true; but into heaven itself, now to appear in the presence of God for us." (Hebrews 9:24) "Neither by the blood of goats and calves, but by his own blood he entered in once into the holy place, having obtained eternal redemption for us" (Hebrews 9:12)
The commandment of "It shall be a sabbath of rest unto you, and ye shall afflict your souls, by a statute for ever (Vayikra - Leviticus 16:31)" produced an entire day of fasting and praying. This was observed both individually and also corporately/nationally.
Based on the instruction of Adonai to "afflict your souls and do no work at all...It shall be a sabbath of rest unto you" in Leviticus 16:29-31; Leviticus 23:27-28; and Numbers 29:7, a national fast day is set aside and and a sabbath day is observed (...And ye shall do no work in that same day" Leviticus 23:28).
Although not commanded as THE way to afflict one's soul, Jewish interpretation of self affliction/denial is fasting. This understanding comes from the reading of Yesha'yahu (Isaiah) 58:1-12. Note verse three says "Wherefore have we fasted, say they, and thou seest not? wherefore have we afflicted our soul...." After reading this passage, we see the Biblical application of affliction and fasting.
Regardless of how this command is fullfilled (that is, whether or not you choose fasting as your means of obedience to afflict...or ultimately another way), we need to understand that on this day WE ARE to repent and mourn over our sins and lack of fellowship with our Maker as emphasised in Vayikra (Leviticus) 23:29-30.
Torah reading for morning of Yom Kippur- Lev. 16:1-34 + Num. 29:7-11
Haftarah reading for Yom Kippur morning - Isa. 57:14-58:14
B'rit Hadashah reading for morning of Yom Kippur - Rom. 3:21-26
Torah reading for afternoon of Yom Kippur- Lev. 18:1-30; Jon. 1:1-4:11
Haftarah reading for Yom Kippur afternoon - Mic. 7:18-20
B'rit Hadashah reading for afternoon of Yom Kippur - Heb. 10:1-12
And this shall be a statute for ever unto you: that in the seventh month, on the tenth day of the month, ye shall afflict your souls, and do no work at all, whether it be one of your own country, or a stranger that sojourneth among you: For on that day shall the priest make an atonement for you, to cleanse you, that ye may be clean from all your sins before the LORD. It shall be a sabbath of rest unto you, and ye shall afflict your souls, by a statute for ever. And the priest, whom he shall anoint, and whom he shall consecrate to minister in the priest's office in his father's stead, shall make the atonement, and shall put on the linen clothes, even the holy garments. Vayikra (Leviticus) 16:29-32
Also on the tenth day of this seventh month there shall be a day of atonement: it shall be an holy convocation unto you; and ye shall afflict your souls, and offer an offering made by fire unto the LORD. And ye shall do no work in that same day: for it is a day of atonement, to make an atonement for you before the LORD your God. For whatsoever soul it be that shall not be afflicted in that same day, he shall be cut off from among his people. And whatsoever soul it be that doeth any work in that same day, the same soul will I destroy from among his people. Ye shall do no manner of work: it shall be a statute for ever throughout your generations in all your dwellings. Vayikra (Leviticus) 23:27-31
And ye shall have on the tenth day of this seventh month an holy convocation; and ye shall afflict your souls: ye shall not do any work therein. B'midbar (Numbers) 29:7