Chapter 8. Date Calculation of the Lord’s Feast
We have to know how to figure out the sacred calendar to find the exact date of annual appointed feasts. However, since the feast was largely abolished or altered by the Catholics of the Middle Ages, and the period was over a thousand years old, it is almost impossible for us to find the sacred calendar.
First of all, it is not easy to find out what kinds of feasts existed, and even if you get to know some feasts, it is difficult to find the exact date. Let’s take the Passover as an example. More churches are appearing around the world trying to celebrate the Passover. However, most of them do not know how to calculate the date in the way the Bible tells us, so they celebrate the Passover according to the date that Judaism keeps.
However, it would be surprising, if you hear that the Bible contains all the principles and standards of the sacred calendar, which is needed to make us to find the exact date of the Lord’s feasts. The Church of God Jesus Witnesses thanks to the Lord, who allowed us to calculate the exact date of the feasts based on the principles of the Bible.
The listed below are the principles and criteria needed to calculate the exact date of the feasts.
First, lunar calendar or solar calendar?
Second, new moon or full moon?
Third, lunisolar calendar or lunar calendar
Fourth, what is the standard for the first month of the year?
Fifth, what is the leap month?
Sixth, when start the day of 24 hours?
From now on, let’s check the above six principles one by one through the Bible.
1. Is the sacred calendar the lunar or the solar?
It is relatively easy to know whether God’s feast is based on lunar or solar. Because the Bible tells us directly. According to the Psalms, God said that the feast was set according to the moon’s operation.
【Psa. 104:19】 The moon marks off the seasons, and the sun knows when to go down.
【Psa. 81:3】 Sound the ram’s horn at the New Moon, and when the moon is full, on the day of our Feast
The Psalms show that the Israelites used the new moon and the full moon. These records indicate that the Israelites used the lunar calendar established by the moon’s operation. In addition, it can be seen that the concept of the time of one month is based on two knots: new moon and full moon during the operation of the moon.
2. What is the reference point for a month? The new moon or the full moon?
Which one is the starting piont of one month? New moon or full moon? The time when the moon and the sun are in the same direction is called the ‘new moon’, and the time when the moon and the sun are in opposite directions around the earth is called the ‘full moon’. The time duration from the new moon to the next new moon or from the full moon to the next full moon is called the synodic month. The average length of the synodic month is 29.53 days. Earth’s orbit around the sun is elliptical. If the earth orbits quickly at a distance close to the sun, the moon also follows the earth and orbits for longer, resulting in a longer synodic month. Therefore, depending on the change in the distance between the Earth and the Sun, the length of the synodic month is changeable approximately 29.2 to 29.8 days.
In the case of the lunar calendar worldwide, the day at which the new moon is located is defined as the beginning of the month. This principle applies equally to the sacred calendar to caculate the Lord’s feasts. This principle is confirmed by the fact that the Israelites recognized the new moon and the first day of a month as the same day.
【Num, 28:11】 On the first of every month(On the new moon), present to the LORD a burnt offering of two young bulls, one ram and seven male lambs a year old, all without defect.
【2Chr. 2:4】”Behold, I am about to build a house for the name of the LORD my God, dedicating it to Him, to burn fragrant incense before Him and to set out the showbread continually, and to offer burnt offerings morning and evening, on sabbaths and on new moons (welehodasim/new moon/וְלֶ֣חֳדָשִׁ֔ים) and on the appointed feasts of the LORD our God, this being required forever in Israel.
It was a rule for the Israelites to offer a burnt offering on the new moon every month.
God established the ordinances to offer sacrifices at the appointed time. According to God-given ordinances, there were the daily burnt offering, the Sabbath day burnt offering, and the new moon burnt offering.
The important fact here was that on the day when two or more sacrifices overlap, each offering had to be offered separately. For example, on the Sabbath day, not only the Sabbath sacrifices were offered, but also the daily offerings offered separately.
【Num. 28:9-10】 On the Sabbath day, make an offering of two lambs a year old without defect, together with its drink offering and a grain offering of two-tenths of an ephah of fine flour mixed with oil.This is the burnt offering for every Sabbath, in addition to the regular burnt offering and its drink offering.
Saying “addition to the regular burnt offering”, on the Sabbath day, the Israelites offered the burnt offering of two lambs and the regular burnt offering also. In the same way, on the new moon, the Israelites offered the burnt offering and offered the regular burnt offering separately.
【Num. 28:11-15】On the first of every month, present to the LORD a burnt offering of two young bulls, one ram and seven male lambs a year old, all without defect …… Besides the regular burnt offering with its drink offering, one male goat is to be presented to the LORD as a sin offering.
Saying “Besides the regular burnt offering with its drink offering”, the Israelites offered the burnt offering on the new moon and offered the regular burnt offering separately.
Among the ordinances of the Feast of Trumpet, there is a very meaningful word. The regular burnt offering and the new moon burnt offering must be done on the 1st day of the seventh month separately from the sacrifice for the Feast of Trumpet.
【Num. 29:1-6】 On the first day of the seventh month hold a sacred assembly and do no regular work. It is a day for you to sound the trumpets …… These are in addition to the monthly (hahodes/new moon/הַחֹ֜דֶשׁ) and daily burnt offerings
Because God ordered Israelites to offer sacrifice for the Feast of Trumpet and offer the new moon burnt offering on the same day, the new moon must be the 1st day of the month. Therefore, it is evident that the standard for determining the first day of the month in keeping the feast of God in the Bible is the day of the new moon.
3. What is the Bible calendar? Lunisolar calendar or lunar calendar?
Among the feasts of God, there is the Feast of First-fruit, which is the day after the Sabbath that comes just after the Feast of Unleavened Bread. The Feast of First-fruit is a feast to set the day of the week, so the date is somewhat different every year. According to the ordinance of the feast, when the Israelites reap their harvest, they have to bring to the priest a sheaf of the first grain they harvest.
【Lev. 23:6-11】On the fifteenth day of that month the LORD’s Feast of Unleavened Bread begins; for seven days you must eat bread made without yeast …… When you enter the land I am going to give you and you reap its harvest, bring to the priest a sheaf of the first grainyou harvest. He is to wave the sheaf before the LORD so it will be accepted on your behalf; the priest is to wave it on the day after the Sabbath.
In order to bring a sheaf of the first grain they harvest, the Feast of First-fruit should be observed in the proper season for the wheat harvest. To meet the season for the wheat harvest, the sacred calendar must be the lunisolar calendar.
The Israelites had to keep the Feast of First-fruit to bring a sheaf of the first grain they harvest. It means that they couldn’t rest for the harvest. Unlike the other feasts, the day after the Sabbath was not a day of rest, but rather a day of harvest.
【1Cor. 16:1-2】 Now about the collection for God’s people: Do what I told the Galatian churches to do. On the first day of every week, each one of you should set aside a sum of money in keeping with his income, saving it up, so that when I come no collections will have to be made.
God is pleased with the first fruit. The apostle Paul also taught that it is the correct attitude of the Christian to use the income earned by working on the first day as the offering for the church.
4. What is the standard for the first month of a year?
At the time of Exodus, God told Moses which month the first month of the year was. And on the 14th of that month, God brought the 10th last plague to the Egyptians. Pharaoh, who was plagued with Passover, allowed the Israelites to leave Egypt. The Israelites’ exodus occurred on the 15th of the very first month.
【Exod. 12:1-2】 The LORD said to Moses and Aaron in Egypt, “This month is to be for you the first month, the first month of your year.
So, which season was the first month of the year God told Moses? If you look closely at the records of the ten plagues that fell upon Egypt at that time, you can find a key to know which season it was.
【Exod. 9:25, 31-32】 Throughout Egypt hail struck everything in the fields–both men and animals; it beat down everything growing in the fields and stripped every tree …… The flax and barley were destroyed, since the barley had headed and the flax was in bloom. The wheat and spelt, however, were not destroyed, because they ripen later.
Hail was the seventh plague in Egypt. The above verse records the damage of various crops caused by the hail disaster. The record that ‘barley comes out and the flowers bloomed’ shows that the season of hail disaster was spring. And after all ten plagues, the Israelites left Egypt on the first month of the year and crossed the Red Sea. The day when the Israelites crossed the Red Sea was instituted as the appointed feast to bring to the priest a sheaf of the first grain. The grain was the wheat, because it was the spring season.
【Lev. 23:10】 “Speak to the Israelites and say to them: ‘When you enter the land I am going to give you and you reap its harvest, bring to the priest a sheaf of the first grain you harvest.
【Exod. 34:22】 Celebrate the Feast of Weeks with the firstfruits of the wheat harvest
God announced the first month of the year and delivered the Israelites from Egypt in that month. And the feasts of God were instituted according to the works of Moses, who delivered the Israelites from Egypt. So why did God set the first month of the year for the spring season?
It was from the creation that God made sun and moon serve as signs to mark seasons and days and years. And all of them was given by the operation of the universe, that is, the operation of the sun, moon, and stars. We can say that God’s feast was already scheduled from the time of creation.
【Gen. 1:14】 And God said, “Let there be lights in the expanse of the sky to separate the day from the night, and let them serve as signs to mark seasons and days and years,
Through the creation of the third day, God created a day of 24 hours and He called the light “day,” and the darkness he called “night.” And God also created the time of one month through the orbit of the moon and the four seasons through the orbit of the earth. And at each of those time frames, there are some knots to measure the time.
The knots of a day of 24 hours are sunrise and sunset. The knots of time that make up a month are new moon and full moon. The knots of time that makes up a year are four seasons. From now on, we are to study which of the knots should be the starting point of the time.
In the case of a day, sunrise is the starting point of the day. Sunrise completes a day of 24-hours by passing the sunset and becoming a new sunrise. In the case of a month, new moon becomes the starting point of the month. When the new moon passes through the full moon and falls into the next new moon, a month is completed.
The concept of periodic repetition, day or month, was understood by the ancients as a cycle of the birth and death of life. They considered that Light was the source of life, and it was their concept that the appearance of light meant birth, and the disappearance of light meant death. The sunrise is a beginning of the light, that is, the birth of life, so the starting point of a day must be sunrise. This idea is very natural once you understand the principles of creation. With the same reason, it is natural that the the starting point of a month must be the new moon.
Let’s look at the changes in the four seasons while thinking about the cycle of the birth and death of life. Spring is the season of birth when all things get birth, and winter is the season of death when all life enters into the ground. Therefore, based upon the the principle of creation, the starting point of a year must be on the spring season. As we reviewed already there are the knots of every time frame. In case of a year, the knot of spring season is the vernal equinox. In the spring season, there can be no other knot except for the vernal equinox.
In summary, it is a natural concept that follows the principle of creation, that the vernal equinox is the standard for determining the first month of a year. And the same concept applies to the starting point of a day or a month.
We can also confirm in the Bible that the vernal equinox is the starting point of the year.
【2 Sam 11:1, 1 Chronicles 20:1】 In the spring, at the time when kings go off to war, David sent Joab out with the king’s men
In the verse above(NIV, NASB, NRSV), “In the spring” was translated as ‘after the year was expired’ by KJV. This is the biblical evidence that the beginning of the year of the sacred calendar is based on the vernal equinox.
【1 Kings 20:22, 20:26】 because next spring the king of Aram will attack you again
In the verse above(NIV, NRSV), “next spring” was translated as “at the return of the year” by KJV and NASB. The Bible confirms that the beginning of the year is in the spring.
【2 Chronicles 36:10】 In the spring, King Nebuchadnezzar sent for him and brought him to Babylon
In the verse above(NIV), “In the spring” was translated as ‘When the year was expired” by KJV, as “At the turn of the year” by NASB, and as “In the spring of the year” by NRSB. It is the passage that confirms that the beginning of the year is in the spring.
5. What is the principle of the leap month
The lunisolar calendar is the lunar calendar which is adjusted to match the seasons of the solar calendar. In order to match the 12 synodic month with one solar year, the extra leap month is needed for every three years. If you calculate correctly, it will be seven extra months every 19 years. The important issue here is the location where we have to put the extra month through out the year.
If you study God’s feast in the Bible, God has established seven feasts from the first month through the seventh month of the sacred calendar. And all of those feasts were established to commemorate Moses’ deeds during the period of their exodus, and became a shadow of what Christ would do in future. In the course of Moses’ deeds, there was a period of 120 days from the day Moses went up to Mount Sinai to receive the first ten commandments(the Feast of Weeks, the 11th day of the third month) to the day he received the second ten commandments (the Day of Atonement, the tenth day of the seventh month). Since these Moses’ deed of 120 days was a shadow for Jesus, it is impossible to put the extra month in the middle of that period.
Today, Jews consider the leap month as the month of Adar which is the last month of a year. They call it the second Adar. Their custom looks so biblical not to undermine the will of God. In case of the Korean lunisolar calendar, the leap month can be located on any of the 12 synodic months. If you follow the Korean method, the seventh month of the sacred calendar would be changed into the eighth month. It will take around 150 days from the Feast of Unleavened Bread(1/15) to the Feast of Tabernacles(7/15). If then, the date of the Feast of Tabernacles will be one month different from the Bible.
6. When does the day of 24 hours start?
As already explained above, the starting point of a day is sunrise. And the starting point a month is the new moon. It means that the day which contains the exact time of the new moon is the first day of the month. We should be careful when setting the day, because the biblical starting point of a day is different from the current calendar.
OK, let’s suppose that 3:00 am is the new moon. In the current calendar, the midnight is the starting point of a day, so the next day which contains the new moon 3:00 am becomes the first day of the month. But according to the Bible, the sunrise is the starting point of a day, so the last day(Yesterday) in which the time of new moon belongs becomes the first day of the month.
According to the time method we use today, the starting point of a day is midnight. But biblically it is sunrise. However, some churches argue that sunset is the starting point of a day. In calculating the date of God’s feast, a lot of explanation must be followed in order to biblically confirm that the standard of the day is sunrise, not sunset. For readers who are curious, I would like to take a separate chapter and take a closer look.
7. How to calculate the sacred calendar for 2024
First, in order to calculate the sacred calendar for 2024, we need to find out which synodic month is the first month of the year. Then, you have to make a lineup that tells you the date and time of the new moon and the full moon. Fortunately, you can search the Internet for information about the synodic months of a year.
You should find out which synodic month of the above 13 rows is the month closest to the vernal equinox. The vernal equinox in 2024 is 12:06:24 on March 20, so the new moon corresponding to the third row in the table above becomes the first month of the year.
In the third row of the above table, the time of the new moon is 18:00:25 on March 10, so the day of March 10 is the first day of the first month based on the sunrise. Therefore, the Passover of 2024, which is the 14th day of the first month, is March 23.
If so, the seventh month of the Bible calendar is the synodic month of the ninth row above. The time of the new moon of the ninth row is 10:55:35 on September 3. So September 3 is the first day of the seventh month based on the sunrise. We must keep the Feast of Trumpet on September 3, 2024.
8. How to calculate the sacred calendar for 2025
The synodic month table for 2025 is as below.
You should find out which synodic month of the above 12 rows is the month closest to the vernal equinox. The vernal equinox in 2025 is 18:01:28 on March 20, so the new moon corresponding to the third row in the table above becomes the first month of the year.
In the third row of the above table, the time of the new moon is 19:57:49 on March 29, so the day of March 29 is the first day of the first month based on the sunrise. Therefore, the Passover of 2025, which is the 14th day of the first month, is April 11.
If so, the seventh month of the Bible calendar is the synodic month of the ninth row above. The time of the new moon of the 9th row is 04:54:96 on September 22. The time of 04:54:96 belongs to the day of September 21 based on the sunrise. So September 21 is the first day of the seventh month. We must keep the Feast of Trumpet on September 21, 2025.
