CALENDARS AND BIBLE CALCULATIONS
“And God said, "Let there be lights in the firmament of the heavens to separate the day from the night; and let them be for signs and for seasons and for days and years, and let them be lights in the firmament of the heavens to give light upon the earth." And it was so. And God made the two great lights, the greater light to rule the day, and the lesser light to rule the night; he made the stars also.” (Genesis 1:14-16 RSV)
From the Creation, God has invited us to use the Sun, Moon, and Stars, to measure time. They are there, not only to give light, but are also to be used to establish “seasons and days and years”. Over time, men have devised many different calendars to measure time. It should be no surprise to us that most of these have been related in some way, to the relative movements of the Sun, and Moon, and Planet Earth, just as God intended.
Bible students sometimes find themselves in a quandary as to which calendar is meant in places where historical events are identified with a particular year, day, or month, which is not related to one of our modern calendars. For those who do find themselves wanting to relate past historical events to our modern Gregorian calendar, there are many difficulties. It takes only a little research to discover that there are many areas where “experts” differ in their conclusions, and information is not nearly as reliable as we would like it to be.
The calendars of ancient civilisations were not always in perfect harmony with the cycles of the Sun, Moon, and Stars. In some civilisations, the seasons did not always occur at the same time in the year. Records about the Calendars of ancient civilisations are often incomplete, or more often, completely lacking. Often the gaps have to be filled by speculative assumptions.
Another complication is that it is not absolutely certain that a solar year, or a lunar month, have always been the same length as they are today. For instance, there are many who speculate that there might have been some sort of change at the time of Noah's flood. (However, it must be emphasised that the key word in that subject is definitely “speculation”!)
There are four main calendars which are of interest to Bible Students.
1. THE SOLAR YEAR AND THE GREGORIAN CALENDAR
The Gregorian Calendar replaced the earlier Julian calendar introduced by Julius Caesar. It was introduced in Catholic countries in 1582, when a correction of 10 days became necessary due to the slight inaccuracy of the Julian calendar. (Britain and her colonies did not adopt it until 1752, by which time the necessary adjustment was 11 days)
The mean solar year is actually 365.2425 days. (The true solar year can vary from the mean by several minutes) In practice the Gregorian calendar uses a 365 day year, balancing the inaccuracy by adding an extra day every fourth year (leap year). To further compensate, leap years are omitted at the turn of each century, unless the century year is divisible by four hundred. (Thus the year 2000 will be a leap year, while century years like 1900 or 2100, are not leap years)
The Gregorian Calendar is slower than the true mean solar year, by about three days in approximately 10,000 years.
2. THE JEWISH CALENDAR
In any given Jewish year, the current equivalent to a Gregorian Year can be calculated by adding 3761. However, since the Jewish year starts around September/October Gregorian time, it spans two successive Gregorian Years. The current Jewish civil year is 5758 (calculated from creation) It begins 2 October 1997, and ends 20 September 1998.
The Jewish Calendar of the Old Testament is mentioned only incidentally to other subjects. It is clearly linked to both Lunar and Solar cycles, but lacks information about how the Lunar year was adjusted to the Solar year, to keep it in step with the seasons and the harvests (which was necessary for the proper observance of the annual festivals).
The current Hebrew calendar was brought back from Babylon by the exiles, when they returned from captivity, in the sixth century BC. For centuries after that, the religious leaders kept secret the details used for the calculation of the annual adjustments. It appears that during that time, the rules were also subject to controversy, contradiction, and variation, depending on who interpreted them. In an endeavour to settle controversy, they were eventually published in fourth century AD, in (more or less) the form which exists today. But disagreement continued at least till the 10th century AD, about the date of creation, and the proper years for adding the extra months.
There is considerable uncertainty about exactly how it was applied over the centuries before it became “fixed”. Records are not available. Many of the factors affecting decisions about when to start a particular month were quite flexible. Lambs had to be mature enough for slaughter on 14 Nisan, the Day of Preparation for the Passover. Crops had to be ripe enough for presentation at the Feast Of The Firstfruits on 16 Nisan, immediately following the Passover. The Jews were very meticulous about such details of their religion. Consequently these festival constraints could be expected to make it fairly certain that some corrections must have been applied to the Calendar, in order to keep the Passover close to its correct place in the seasons of the solar year.
The Jewish calendar is considerably more complex than the Gregorian. It uses "lunar" months as the basis of calculations. However, since a lunar month is not equal to an exact number of days, this approach makes all sorts of difficulties for the Jews, and for ourselves also. (The mean time between two full moons, is actually 29 days, 12 hours, 44 minutes, 2.864 seconds.)
The “standard” Jewish lunar year is 354 days, with 12 months. Ten of the months are of fixed length, some 29 and some 30 days. The other two can both be alternately sometimes 29, and sometimes 30 days, depending on the need to adjust the length of the year slightly.
If not corrected on a regular basis, this would result in the seasons “moving” within the year. For this reason it is necessary in some years, to add an extra month so as to keep the Passover in its proper place in the seasons. In ancient times, it seems most likely that this need for the extra month would have been determined by the requirement for the barley to be ripe before 16 Nisan . The current practice is to add an intercalary month, 7 times in each 19 year cycle. Thus 19 Hebrew calendar years total 235 lunar months.
All of this means that, depending where it falls in the 19 year cycle, a particular year can have 354, 355, 383 or 384 days. An average Jewish year has 365.days, resulting in a “drift” of one day slower than the solar year, each 216 years. (and it is slower than the Gregorian calendar by one day in 231 years.) This means that the Festivals are now celebrated some 8 days later in the solar year, than when the calendar was first published in its present form. (359 AD)
The Jews have a sacred year and a civil year. The sacred year begins in the month Nisan, complying with God's decree in Exodus 12:2. This is the month in which the Feast of the Passover occurs. The civil year begins six months later in Tishri, the seventh month of the sacred year. This is the month in which the Day of Atonement occurs.
Because of the regular corrections made to balance the current Jewish Calendar with the Solar year, it is very close to the Gregorian calendar. However, precise calculations to convert between the two, over long periods of time, must take account of the minor differences described above.
In ancient times, the pattern for the application of the several adjustments is not easy to determine. When looking backwards over long periods of time, it is well nigh impossible to calculate the exact Gregorian date and day of the week for a particular Festival such as the Passover, (especially surrounding the time when Jesus was crucified ..... more about that below.).
3. THE “PRE-FLOOD” CALENDAR
There are some who speculate that the pre-flood movements of Earth and Moon in relation to the Sun, were different to those we experience today. This speculation is based on the Genesis record of the flood. In Genesis 7:11, Noah's flood began on the 17th day of the second month and the ark came to rest 150 days later on the 17th day of the seventh month. (Genesis 8:4) Many have concluded that Moses was speaking of 5 months each exactly 30 days. They then extrapolate from this to claim that God's original “creation year” was 12 months of 360 days.
However that conclusion may be far too simple and speculative. It is certainly open to an equally valid speculation, that Moses meant 5 months totalling 150 days, but only averaging 30 days each!
For instance, compare this with our Gregorian calendar, using the 5 months, 17 February to 17 July. They are not of equal length, but they do total 150 days from the seventeenth day of the second month, to the seventeenth day of the seventh month! Co-incidence? Or is it possible that God is trying to tell us something?
Further, even if a “standard” month was always 30 days, before the flood, there is nothing at all in Genesis to tell us the length of either a “standard” year, or an “average” year. And even if a “standard year” in Noah's time was always 12 months, totalling 360 days, that still does not allow for the probability that the true solar year might have been exactly the same as now, with the calendar requiring regular cyclical “adjustments” of some kind (just as both the modern Jewish and Gregorian calendars do).
There is certainly no clearly written Biblical justification for transposing this assumed “pre-flood” calendar to other events, either before or after the flood.
The practice remains firmly in the realms of speculation .
4. THE "PROPHETIC" CALENDAR
Apart from that speculative conclusion just described above, there are a few prophecies which are often linked to justify the use of a 30 day month and a 360 day year, to measure the time period from start to completion. e.g. Daniel 7:25, Daniel 12:7, Rev 11:2-3 & Rev 12:14.
But a problem arises when some "interpreters" of prophecy loosely transpose this "prophetic year", and at the same time, apply the year for a day method to other prophecies ..... not always with clear justification.
It certainly may be applicable in the few places where it is mentioned. However, it is by no means as clear that it is valid to translate it to other prophecies, when it is not specifically mentioned in those other places,
THE “YEAR FOR A DAY” METHOD
A number of prophecies speak of time periods of DAYS. However, literal days do not always seem to be intended. Many Bible students turn to the “year for a day” method of “interpretation”. This substitutes years in place of days, when it seems more appropriate to consider a longer time span for the fulfilment.
Based on conclusions about a starting point, calculations are then made which try to fit specific later events in history to the time period of the prophecy. (And, it must be admitted that some expositors seem to give the impression of starting with a desired finish point and then working backwards, determined to make it fit!)
On a more positive side, there is a reference in Numbers 14:32-35, where God decreed a punishment of 40 years on Israel, one year for each day in which they had spied out the land.
And, there is another even more specific reference in Ezekiel 4:4-6, where for one particular prophecy, a day is specifically stated by God to represent a year of actual future time.
But, are we justified in translating that to other prophecies? Some think so. Others reject it.
DANIEL'S SEVENTY WEEKS AND THE “YEAR FOR A DAY” METHOD
In the book of Daniel there is a prophecy which refers to a time period of “seventy weeks”, from start to fulfilment. The actual phrase used in the RSV translation Daniel 9:24, is “seventy weeks of years”, Other translations (KJV, NASB, NEB) say “seventy weeks”. However, some commentators tell us that a literal rendition would be “ seventy sevens ”. The NIV translation uses this latter term.
In Hebrew, it seems that this term can mean either a week of days , or a week of years , depending on the context. The Jews did use language this way. Exodus 16:29, specifically refers to a week of seven literal days. On the other hand, Leviticus 25:2-4, refers to a “sabbath week” of seven years; and Leviticus 25:8 to a Jubilee of seven Sabbaths of years.
Daniel does not clearly specify whether he means literal weeks of days, or weeks of years . However the translators of some modern versions (RSV for instance) and most commentators, are agreed that in this place, the context clearly requires years .
Many use this particular reference to support use
THE MILLENNIUM FOR A DAY THEORY
This one uses “millennia” in place of “days” for the prophecy in Hosea 6:1-3. In this case it is suggested that Hosea is prophesying about the restoration of Israel in the third millennium from the time of the prophecy.
This is sometimes loosely justified by quoting Psalm 90:4 and/or 2 Peter 3:8, “ With the Lord, one day is as a thousand years, and a thousand years as one day ”.
In another application of this theory, the seven days of the Creation week are claimed to represent seven millennia, as the time allotted for the completion of God's plan with Creation. This present era is predicted to terminate 6000 years after creation, to be followed by a “sabbath millennium” of 1000 years.
CALCULATING THE AGE OF THE EARTH FROM THE BIBLE RECORDS
There have been many attempts to calculate the age of the earth, using the time periods listed in various places. Many of the genealogies give ages of men when their sons were born, or when they died. The lengths of the reign of various kings are another source of input data.
However, while this can result in useful approximate totals, there are a number of factors which affect the absolute accuracy of any such calculation.
The main problem is the Jewish method of reckoning numbers, which counts parts of years as whole numbers. i.e. A man might be born in the 500th year of his fathers life. However the first year of his father's life might have been only the last month or so of the then current calendar year. The birth might have taken place very early in the 500th year. Both would be counted as years by Jewish reckoning, but they would actually total less than one year of calendar time ..... not two ! Obviously such errors might be multiplied.
The same difficulty applies to the lengths of the reign of the kings.
Another factor is that some dates are not mentioned at all, and require speculative assumptions to fill the gaps. (such as some of the periods in history when Israel was ruled by the judges.)
One of the best known calculations of the age of the earth, was made by Archbishop Ussher in 1650AD. Ussher dated creation at 4004BC. But there have been many attempts by others, which produced considerably different results.
For example, the Jewish calculation dates Creation at 3760BC.
CALCULATING BY THE “YEAR FOR A DAY” METHOD
Whilst it seems fairly clear that, for some prophecies at least, we are meant to use this method, there are considerable difficulties in deciding reliable starting points in history, and which calendar should be used.
For things Jewish, it would seem valid to use the “standard” Hebrew Calendar for such calculations. (including regular cyclical adjustments to conform with the solar year)
Other factors which may need to be resolved are :-
1. Is there any possible validity for the use of the “Prophetic” calendar instead of the Hebrew?
2. Have we read enough of the relevant history to be personally certain of our facts? Or are we merely
exercising the “gift of credulity”, in taking another man's word about the History?
3. Is the starting point of our “base historical data” reliable?
4. Can we arrive at an end point which can be reliably confirmed?
5. How do we know our sources are reliable? Who says so? And how do we prove that? Or are we amongst
all those other gullible and credulous people who simply regurgitate the mistakes of others?
If we are not meticulously honest about this,
CALCULATING THE DATE OF THE CRUCIFIXION PASSOVER- A NEAR IMPOSSIBLE CALCULATION?
The consensus of the gospels is that the crucifixion took place on the Preparation day for the Passover feast, when the Passover lamb was sacrificed. (This would have been 14 Nisan). It also seems clear that for that year, the Passover coincided with the Jewish weekly Sabbath. This would settle Friday as the Crucifixion day.
If only we knew for certain how the calendar rules were applied around that time, it would seem to be a fairly simple matter to calculate the date of the Crucifixion, by finding a year in which the afternoon of 14 Nisan fell on a Friday.
Another way would be to determine the date of the new moon for the first day of Nisan, by astronomical calculations, and then extrapolate to 14 Nisan.
However, neither of these can guarantee absolute certainty. The application of the Hebrew calendar in the first century AD is not adequately documented. There is no way to be certain about exactly when extra months or days were added to the calendar. And there is also uncertainty about how reliably the calendar was followed at particular times in Jewish history.
Further, it appears that, at that time, the actual sighting of the New Moon was the real determining factor in setting the start of the month. In the event of cloudy conditions, a special committee of the Sanhedrin made an arbitrary decision, which while self correcting over a year, could easily result in occasional errors of a day for any month during the year.
For all these reasons, while it may be possible to calculate an acceptable correlation between a particular Jewish and Gregorian year, there is great difficulty in determining the same correlation for a particular day and month for that year. For a Passover around the time of the crucifixion of Jesus, according to some authorities, it is virtually impossible.
I have in my possession no less than three different computer programs, all of which claim to be able to apply the rules of the Jewish calendar, to the calculation of the date of the Passover in a particular year. (including those around the probable time of the Crucifixion.) For all three, the answer appears in an instant.
Alas ..... all three give different dates, and/or days of the week, for the crucifixion!
WHEN WILL JESUS RETURN? - THE DEFINITELY IMPOSSIBLE CALCULATION!
Over the history of the Church, many have claimed to be able to calculate the date of the return of Jesus. Most have used one version or another of the calendar information above, in conjunction with prophecies which mention time periods. And many have been led astray by those claims . (Matthew 24:4-5, 23-24)
By these false claims, the cause of Christ has been exposed to great ridicule amongst unbelievers.
Associated with many of these mistaken predictions, there are records of people who sold houses and possessions, or left employment as the time approached, and then went to wait at a nominated location. In my childhood my parents told me of one family who, in expectation of the immediate return of Jesus, purchased goods on credit, not expecting to have to pay! And in the early years of this century, in Sydney, Australia, at least one man sought to make commercial gain, by selling tickets to grandstands specially constructed to view the event!
Of course, they were all wrong. Some made a big impact on many people, at the time. But only a fraction of them are recorded in the written history of the many false prophets, predicted by Jesus!
Jesus Himself said “Of that day and hour no one knows, not even the Angels of heaven, nor the Son, but the Father only ”. (Matthew 24:36) And Jesus also said “ It is not for you to know the times or the seasons which the Father has fixed by His own authority ” (Acts 1:7)
Nowhere in Scripture has Jesus changed that warning!
CAREFUL! - THERE IS NO YEAR “ZERO”!
One of the common errors of calculating dates which span BC to AD, is associated with the fact that there is no year zero . One simple calculation will suffice to show where the problem lies.
Adding 10 years from part way through BC5 brings us to the same place in the year AD6 ..... not AD5 !
Look at it this way ..... April BC5 plus 5 years comes to April AD1. April AD1 plus 5 years comes to April AD6.
Beware the trap! Many “private interpretations” fall down at this point!
DECIDING WHICH CALENDAR TO USE
In Biblical terms, calendars are important to those who feel a need to calculate dates for past and future historical events. Equally, for others who speculate about the meaning of a number of Old and New Testament prophecies, and especially those who use the “year for a day method”, the credibility of the result depends on selection of the correct calendar.
For many, the choice seems to fluctuate between the four described above (and sometimes inaccurate variations of those methods!) depending on which happens to suit the desired result and the expediency of the moment! Lest we join the many false prophets, we do need to be totally honest and very prayerfully objective about our assumptions.
Better not to prophesy at all, than to be dogmatic and then be found wrong. (Deut 18:20-22) And if we must speak at all, let us not be hasty to claim something near “inspiration” for a merely “private interpretation”.
This paper does not presume to tell you which calendar to use for your own study of prophecy. It merely describes some of the available alternatives, and lists some of the difficulties which must not be ignored .
For what it is worth, I presently think that unless there are obvious compelling reasons otherwise, the default choice should be to use a Hebrew lunar calendar, which periodically adjusts to the correct length of a solar year. Over long periods of time, give or take a few days, that will prove to be almost the same as using the Gregorian calendar.
And I might occasionally have yet another dabble with the “year for a day” method, just to see what pops up!
But ..... my major conclusion about choosing a calendar to use?
It isn't always easy ..... And sometimes it doesn't seem possible to be definite at all!
WHY SHOULD IT ALL BE SO APPARENTLY DIFFICULT?
Does God sometimes deliberately give information without the key to unlock its meaning?
Indeed, it seems that He does!
INSPIRED INTERPRETATION, OR PRIVATE?
Of course it isn't always enough to have correct information about which calendar to use! Peter tells us that it requires the same Holy Spirit to understand a prophecy, as it did to inspire it in the first place. Without the Holy Spirit, men can only produce “private interpretations”! (2 Peter 1:20-21)
We may also say, reverently, that it requires the same Holy Spirit to recognise some of the many cleverly contrived private interpretations from uninspired men, for what they really are.
And it takes the same Holy Spirit to know that sometimes God has not yet opened our own minds to understand the interpretation, at all!
Getting that right, requires far more than mere academic ability!
This study began when our midweek Bible class decided to take a fresh look at some of the fulfilled prophecies of the Book of Daniel. But, that led immediately to another question. Why might one calendar be more preferable to another, when trying to come to grips with the Seventy Weeks Prophecy of Daniel Chapter 9? We still haven't completed the study of the prophecy itself. But at least we now have some of the background information. Now we have to decide what to do with it!
But first, we have to answer some new questions about the history. And second, we have to wade through the pros and cons of the mass of conflicting interpretations, from historicist and futurist sources. And third, we have to allocate it a priority alongside what we see as other more essential kingdom issues. I personally don't expect any of that to happen overnight! And I certainly don't want to “prophesy” about when it might come to pass!
I certainly don't want to discourage anyone from prayerful search to understand things God has written.
But I do see a need for many people who are writing the current crop of books and articles on prophecy, to be a lot more careful. And I do want to sound the obvious warning about the mass of confusion that surrounds this subject .
“Of making many books there is no end, and much study is a weariness of the flesh.” (Ecclesiastes 12:12)
How true that is! Countless books have been written on the subject ..... all different! And it seems that almost every Bible College has its own different “flavour”, often depending on who the resident professor is for that year. They can't all be right !
How important it is that we humble ourselves to accept that our own feeble attempts to understand, may run far ahead of God! If we are not careful about that, we will produce just one more, amongst the many other uninspired and merely “Private Interpretations” that have plagued the Church for all of its history.
How important it is that we remain sensitive to God's Holy Spirit, both to be taught, and also, often, to know only that we do not yet know ! (1 Corinthians 13:12)
The most important thing of all, is that we should first pursue the goal of loving Jesus and obeying Jesus. Only that guarantees that we will receive the same Holy Spirit by which the prophecies were first inspired. (John 14:15-17, 26 & Acts 5:32)
And if the Holy Spirit is our teacher, then perhaps we can learn to be honest with ourselves about the difference between things that we do know beyond question, and those other things which God has not yet fully revealed to us.
Our most important conclusion?
Our greatest need is to get those priorities in their correct order!