The Day of Atonement a TWO DAY Observance
Lev. 23:26 And the LORD spake unto Moses, saying,
:27 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.
:28 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.
:29 For whatsoever soul it be that shall not be afflicted in that same day, he shall be cut off from among his people.
:30 And whatsoever soul it be that doeth any work in that same day, the same soul will I destroy from among his people.
:31 Ye shall do no manner of work: it shall be a statute for ever throughout your generations in all your dwellings.
:32 It shall be unto you a sabbath of rest, and ye shall afflict your souls: in the ninth dayof the month at even, from even unto even, shall ye celebrate your sabbath.
It plainly says the Day of Atonement is the 10th Day (vs. 27)! It is the same day! It says it is "that same day" in verse 28, 29 and 30! The confusion comes about where it says 9th day from even to even in verse 32. This is the ONLY Sabbath or Holy day where it uses this phrase of "from even unto even". This is also the ONLY time this phrase "even unto even" in the entire Bible! That is interesting! (the closest to it is Unleavened bread which we will discuss in just a minute.) What is unique or different about The Day of Atonement? It is the ONLY day that we are commanded to fast on a particular day. Most fast days are considered minor fast days. That means the fast usually lasts from sunrise to sunset. (Source 1, Source 2. On these days, breakfast is permitted if eaten before sunrise. But the Day of Atonement is Different. It is a Major Commanded Fast. It would not do any good to eat a breakfast and then proclaim your fast and say "I'm going to fast now Lord", when you just finished stuffing your stomach! No, you must have your stomach empty or near empty at the beginning of your Day of Atonement Fast! So that is why the Lord wants you to start your fasting on the evening of the 9th. But the actual Holy Day is the 10th as it says it is. We understand now why God would want us to START our fast "from" the previous evening. You are fasting from sunrise (which is the beginning of the 10th) until sunset on the 10th because the Holy Day is ON THE 10TH. But you start fasting on the 9th so that your stomach is empty by the 10th, for a true humbling fast.
Let's also take a look at the Feast of Unleavened Bread:
We are commanded to eat Unleavened Bread from even to even.
Exodus 12:18: "In the first month, ON the fourteenth day of the month at even, you shall eat unleavened bread, until the one and twentieth day of the month at even".
It is NOT saying that the day starts at evening. It says "ON THE 14th Day". NOT "beginning the 14th day". What it is saying, is that we are to EAT unleavened bread from even to even. What does Atonement and the Passover Season have in Common? They are both types of fast. During the Days of Unleavened Bread, you are fasting from leavening. Therefore, you start fasting from leavening at sunset on Passover evening, which is the evening before the first day of Unleavened Bread. In the same way that GOD wants our stomach empty when the Day of Atonement starts at sunrise on the 10th of the 7th month, HE also wants us to start the process of removing leavening from our lives as soon as we partake of symbolically HIS Body and Blood on Passover. This also represents that as soon as we surrender to HIM, that the process of removing sin from our lives start. Although HE forgives us of our sins as soon as we surrender to HIM, it is a life long journey of learning and unlearning and growing in HIS Will.
The Passover observance/meal (although the day starts at sunrise, actually twilight) is eaten at sunset. It is a solemn observance remembering Christ sacrifice, that we are Saved by HIS Body and Blood, represented by the unleavened bread and wine.
The Night To Be Much Observed is the night after Passover. It is the first day of Unleavened Bread. The observance of the Night to be Much Observed starts at sunset, 24 hours after the Passover communion. It represents the night that GOD brought the Israelites (which represent the New Testament Church) out of Egypt (which represents a long journey of the process of removal of sin).
The 7 Days of Unleavened Bread are solemn reminders for us to continue to remove sin from our lives. Philippians 2:12-13
Pentecost is a Day of Celebration. As such, It starts and ends at sunrise and has NO commandment to do anything at even or until even.
The Feast of Trumpets is also a Day of Celebration. There is NO commandment to do anything at even.
The Day of Atonement is a solemn day. It is on the 10th of the 7th month.
The fasting observance starts at evening on the 9th. Until the evening on the 10th. It reminds us Christ is our atonement.
The 7 Days of the Feast of Tabernacles are days of Celebration and have NO eventide commandment.
The 8th Last Great Day is a Day of Celebration and has NO eventide commandment.
In Matt. 26, We see proof that the Day of Passover/UB starts BEFORE evening comes but is observed at Evening.
Matt. 26:17 Now the first day of the feast of unleavened bread the disciples came to Jesus, saying unto him, Where wilt thou that we prepare for thee to eat the passover?
(it was NOT evening yet, but it is the 1st day of UB!)