Summary: The Day of Atonement in the scriptures was a specific day for fasting, repentance, consecration and sanctification. As Christians we ought to have specific days in our walk of faith to examine our length of spiritual progress.
26 And the Lord spoke to Moses, saying: 27 “Also the tenth day of this seventh month shall be the Day of Atonement. It shall be a holy convocation for you; you shall afflict your souls, and offer an offering made by fire to the Lord. 28 And you shall do no work on that same day, for it is the Day of Atonement, to make atonement for you before the Lord your God. 29 For any person who is not afflicted in soul on that same day shall be cut off from his people. 30 And any person who does any work on that same day, that person I will destroy from among his people. 31 You shall do no manner of work; it shall be a statute forever throughout your generations in all your dwellings. 32 It shall be to you a Sabbath of solemn rest, and you shall afflict your souls; on the ninth day of the month at evening, from evening to evening, you shall celebrate your Sabbath.”
Fasting is much in use at times of mourning, sorrow and afflictions. There is no commandment of fasting, properly so called, to be seen before Moses. It is presumable that the patriarchs fasted since we see that there were very great mourning occasionally among them, such as that of Abraham for Sarah (Genesis 23:2) and Jacob for his son Joseph (Genesis 37:34). Moses enjoins no particular fast, excepting that upon the day of atonement which was generally and strictly observed (Leviticus 23:27,29). After Moses, we see that Joshua and the elders of Israel remained prostrate before the ark of God from morning until evening, without eating after the Israelites were defeated by the men of Ai because of Achan's sin (Joshua 7:6). The Day of Atonement meant expiation or reparation for any wrong done or a day to make amends. The Israelites had to purify themselves, get rid of sin and get right with God. In the above passage from Leviticus, we see four key points to follow on the days of atonement in our spiritual progress:
1) You Shall Afflict Your Soul (verse 27, 29)
The children of Israel had to come together and be sorrowful for their sin. If anyone refused to be afflicted they would be cut off.
God is serious about our repentance. You are afflicting your soul if you are in sorrow and mourning. They are usually followed by no desire for food. People don't throw a party when they are mourning.
Many times we Christians get cosy with sin. God wants us to come out of our comfort zone and be sorrowful about sin. He hates a lukewarm Christian life (Revelation 3:16). The difference between the sorrow of the world and the godly sorrow seen in the scriptures is that the sorrow of the world leads you to depression, worthlessness and suicide but godly sorrow leads you to repentance, joy and a purpose filled life (2 Corinthians 7:10).
2) Offer An Offering Made By Fire Unto The Lord (verse 27)
This meant that the children of Israel had to offer a burnt offering for their sins. Those sacrifices were a reminder of their sins every year. Since it is not possible that the blood of bulls and goats to take away sins (Hebrews 10:3,4) , this act foreshadowed the ultimate sacrifice of Jesus Christ for the sins of the world.