Christians who observe a Saturday Sabbath commonly believe that the Jews have always kept perfect track of when the true Sabbath occurs. The reasoning is this: "The Jews would never worship on any other day but the true Sabbath, therefore, because they themselves worship on Saturday that must be the true Sabbath of the Bible."
It is true that the Jews never lost track of the true Sabbath. However, they did, deliberately and knowingly, change their calendar by which the true Sabbath was calculated. The following quotes, taken from Jewish scholars and historians are but a small sampling of the evidence available to support the fact that the Jews, by their own admission, changed the calendar established by God at Creation and reestablished by Moses. (All emphasis supplied unless otherwise noted.)
The New Moon is still, and the Sabbath originally was, dependent upon the lunar cycle . . . Originally, the New Moon was celebrated in the same way as the Sabbath; gradually it became less important while the Sabbath became more and more a day of religion and humanity, of religious meditation and instruction, of peace and delight of the soul. (Universal Jewish Encyclopedia, "Holidays," p. 410.)
With the development of the importance of the Sabbath as a day of consecration and the emphasis laid upon the significant number seven, the week became more and more divorced from its lunar connection . . . . (Universal Jewish Encyclopedia, Vol. X, "Week," p. 482.)
Under the reign of Constantius (337-362) the persecutions of the Jews reached such a height that . . . the computation of the calendar [was] forbidden under pain of severe punishment" (excerpted from The Jewish Encyclopedia, "Calendar.")
Declaring the new month by observation of the new moon, and the new year by the arrival of spring, can only be done by the Sanhedrin. In the time of Hillel II [4th century A. D.], the last President of the Sanhedrin, the Romans prohibited this practice. Hillel II was therefore forced to institute his fixed calendar, thus in effect giving the Sanhedrin's advance approval to the calendars of all future years." ("The Jewish Calendar and Holidays (incl. Sabbath): The Jewish Calendar: Changing the Calendar," www.torah.org.)
The present Jewish calendar was fixed in the fourth century. (Letter by Louis Finkelstein, Jewish Theological Seminary of America, to Dr. L. E. Froom, Feb. 20, 1939.)
Maimonides and most other Jewish chronologers agree that the modern Jewish calendar is based upon the "mean motions of the sun and moon, the true having been set aside." (Maimonides, Kiddusch Ha-hodesch, Tr. Mahler, Wein, 1889.)
Intercalations [of the calendar] were determined at meetings of a special commission of the Sanhedrin. But Constantius, following the tyrannous precedents of Hadrian, prohibited the holding of such meetings . . . How difficult the fixing of the annual calendar consequently became may be judged from an enigmatic letter addressed to Raba . . . and preserved in the Talmud . . . .
Almost the whole Diaspora depended for the legal observance of the feasts and fasts upon the calendar sanctioned by the Judea Sanhedrin; yet danger threatened the participants in that sanction and the messengers who communicated their decisions to distant congregations. . . . As the religious persecutions continued, Hillel determined to provide an authorized calendar for all time to come, though by so doing he severed the ties which united the Jews of the Diaspora to their mother country and to the patriarchate. (I. Singer and S. Mendelsohn, "Hillel II," www.JewishEncyclopedia.com.)
The months of the year were lunar, and began with the new moon (hodesh, which came to mean "month.") During the era of the Kings the new moon was observed by a two-day festival (I Sam. 20:24-47.) (The Universal Jewish Encyclopedia, "Calendar," p. 631.)
In the fourth century, Hillel II established a fixed calendar based on mathematical and astronomical calculations. This calendar, still in use, standardized the length of months and the addition of months over the course of a 19 year cycle, so that the lunar calendar realigns with the solar years. (Judaism 101, "Jewish Calendar," www.jewfaq.org.)
Since Biblical times the months and years of the Jewish calendar have been established by the cycles of the moon and the sun. The traditional law prescribes that the months shall follow closely the course of the moon . . . In the early times of our history the solution was found by the following practical procedure: The beginnings of the months were determined by direct observation of the new moon.
. . . This method of observation and intercalation was in use throughout the period of the second temple (516 B.C.E. - 70 C.E.), and about three centuries after its destruction, as long as there was an independent Sanhedrin. In the fourth century, however, when oppression and persecution threatened the continued existence of the Sanhedrin, the patriarch Hillel II took an extraordinary step to preserve the unity of Israel . . . he made public the system of calendar calculation which up to then had been a closely guarded secret. It had been used in the past only to check the observations and testimonies of witnesses, and to determine the beginnings of the spring season.
In accordance with this system, Hillel II formally sanctified all months in advance, and intercalated all future leap years until such time as a new, recognized Sanhedrin would be established in Israel. This is the permanent calendar according to which the New Moons and Festivals are calculated and celebrated today by the Jews all over the world. Like the former system of observation, it is based on the Luni-Solar principle. (Arthur Spier, The Comprehensive Hebrew Calendar, excerpted at www.jewishcalendar.com.)
It [the Sabbath] was probably originally connected in some manner with the cult of the moon, as indeed is suggested by the frequent mention of Sabbath and New-Moon festivals in the same sentence (Isa. i. 13; Amos viii. 5; H Kings iv. 23) . . . The Sabbath depending, in Israel's nomadic period, upon the observation of the phases of the moon, it could not, according to this view, be a fixed day . . . . (www.jewishencyclopedia.com, "Sabbath.")
The week of seven days was connected with the lunar month, of which it is, approximately, a fourth. The quadripartite division of the month was evidently in use among the Hebrews and other ancient peoples; but it is not clear whether it originated among the former. It is unnecessary to assume, however, that it was derived from the Babylonians, for it is equally possible that observations of the four phases of the moon led the Hebrew nomads spontaneously and independently to devise the system of dividing the interval between the successive new moons into four groups of seven days each. There is ground, on the other hand, for the assumption that both among the Babylonians and among the Hebrews the first day of the first week of the month was always reckoned as coincident with the first day of the month." (www.jewishencyclopedia.com, "Week.")
When the Dead Sea Scrolls were discovered, archaeologists found several manuscripts which dated, approximately, from the 1st century B.C. What made these particular documents so unusual, however, is that they were for the express purpose of synchronizing the lunar calendar to a longer solar calendar. Archeologists found that two of these scrolls (4Q320 and 4Q321) recorded the beginnings of the solar months and the festivals. A third manuscript, 4Q321a, might also have given this information, but because part of the text had disintegrated over time, it is impossible to know for sure.
The descendants of Aaron were divided into 24 courses for service. The names of these courses are given in I Chron. 24:7-18. All three texts give the priestly rotation for temple service at the time covered. The following quotes show how luni-solar dates correspond to dates on the solar calendar. It is important to note that at this time, the Jews were under the dominion of the Romans and the solar year to which they were comparing the luni-solar dates was likely the Julian calendar or its immediate predecessor.
The following quotations are taken from The Dead Sea Scrolls, translated by Michael Wise, Martin Abegg, Jr., and Edward Cook:
4Q320 Mishmerot A (fragment 1, column 1):
Line 6: [On the fifth day of Jeda]iah is the twenty-ninth day (of the lunar month), on the thirtieth day of the (first solar) month.
Line 12: [On the Sabbath of the course of Seori]m is the twenty-ninth day (of the lunar month), on the twenty-fifth day of the seventh (solar month).
4Q321 Mishmerot Ba (fragment 1, column 1):
Lines 4 and 5: . . . and the first crescent [of the moon] is on the sabbath of the course of Pethahiah, on the ninth of the [solar] month.
4Q321a Mishmerot Bb: This fragment regulates the lunar calendar to the solar for the first year, months two through five.
Line 4: [(The full moon is on the) Sabbath of the course of Koz, on the thirtieth day of the second (solar) month, and the first crescent is on the first day of Malchijah, on the seventeenth] of the month.
Line 5: [(The full moon is) on the first day of Eliashib, on the twenty-ninth day of the third (solar) month, and the first crescent] is on the second day of Jeshua, on the [sixteenth] of the month.
Over time, the observance of the New Moon as a day of consecration dwindled in importance.
In the Diaspora the New Moon came to occupy a secondary position in contrast to the Sabbath; the prohibition against work and the carrying on of commerce was lifted, and the New Moon, although still celebrated by means of increased offerings, soon was reduced to the rank of a minor of half holiday. Its importance was confined to the fact that it remained of great value and necessity for the fixing of the festivals. (Universal Jewish Encyclopedia, "New Moon," Vol. 8, p. 171.
The belief, that the week has come down uninterrupted since Creation, is not an assumption shared by modern Jewish scholars who know their history.
A continuous seven-day cycle that runs throughout history paying no attention whatsoever to the moon and its phases is a distinctly Jewish invention. Moreover, the dissociation of the seven-day week from nature has been one of the most significant contributions of Judaism to civilization. Like the invention of the mechanical clock some 1,500 years later, it facilitates the establishment of what Lewis Mumford identified as "mechanical periodicity," thus essentially increasing the distance between human beings and nature. Quasi [lunar] weeks and [continuous] weeks actually represent two fundamentally distinct modes of temporal organization of human life, the former involving partial adaptation to nature, and the latter stressing total emancipation from it. The invention of the continuous week was therefore one of the most significant breakthroughs in human beings' attempts to break away from being prisoners of nature [and from under God's law] and create a social world of their own. (Eviator Zerubavel, The Seven Day Circle: the History and Meaning of the Week, The Free Press, New York, 1985, p. 11.)
One "proof" given to support belief in a Saturday Sabbath is the fact that the word for the seventh day of the week in many languages is, or bears a resemblance to, the word "Sabbath." This, too, is explained by Zerubavel:
The Jewish and astrological weeks evolved quite independently of one another. However, given the coincidence of their identical length, it was only a matter of time before some permanent correspondence between particular Jewish days and particular planetary days would be made. A permanent correspondence between the Sabbath and "the day of Saturn" was thus established . . . [some time] later than the first century of the present era, Jews even came to name the planet Saturn Shabtai, after the original Hebrew name of the Sabbath, Shabbath. Moreover, as they came into closer contact with Hellenism, their conception of their holy day was evidently affected by the astrological conception of Saturn as a planet that has an overwhelming negative influence (a conception which, incidentally, is still evident even from the association of the English word "saturnine" with a gloomy disposition.) There are traditional Jewish superstitious beliefs about demons and evil spirits that hold full sway on the Sabbath, and an old Jewish legend even links the choice of "the day of Saturn" as the official Jewish rest day with the superstition that it would be an inauspicious day for doing any work anyway! (Ibid., p. 17.)
Zerubavel clearly understands the origins of the ancient Hebrew calendar, as well as the connection to the Creator:
The dissociation of the week from a natural cycle such as the waxing and waning of the moon can be seen as part of a general movement toward introducing a supranatural deity. Not being personified as any particular natural force, the Jewish god was to be regarded as untouched by nature in any way. Accordingly, the day dedicated to this god was to be regarded as part of a divine temporal pattern that transcends even nature itself. That obviously involved dissociating the week from nature and its rhythms. Only by being based on an entirely artificial mathematical rhythm could the Sabbath observance become totally independent of the lunar or any other natural cycle. (Ibid., p. 11.)
The significance of a Creator God who stands separate and above the planetary calendar He has created, was a concept used by Abraham the patriarch when attempting to witness to the Chaldeans in Ur. According to Josephus (c.a., A. D. 37 - A. D. 101), a Chaldean historian, Berosus, mentions Abraham as having great knowledge of astronomy: "In the tenth generation after the Flood, there was among the Chaldeans a man [Abram] righteous and great, and skilful in the celestial science" (as quoted by Josephus in Antiquities of the Jews.)
Unfortunately, the Chaldeans had already apostatized from the worship of the Creator God. In turning from their Creator to the creation, the city of Ur had for its patron god, the moon god, Sin. Josephus states:
He [Abram] was a person of great sagacity [wisdom], both for understanding all things and persuading his hearers, and not mistaken in his opinions; for which reason he began to have higher notions of virtue than others had, and he determined to renew and to change the opinions all men happened then to have concerning God; for he was the first that ventured to publish this notion, that there was but one God, the Creator of the universe; and that, as to other [gods], if they contributed anything to the happiness of men, that each of them afforded it only according to his appointment, and not by their own power. (Antiquities of the Jews, Book I, chapter VII, verse 1.)
The very fact that both the solar and lunar years are differing lengths requiring intercalation (adding extra days or months, respectively, during "leap" years) was used by Abraham to prove that nature itself was not god, but that there was a Being superior to nature that was its Creator:
This his opinion was derived from the irregular phenomena that were visible both at land and sea, as well as those that happen to the sun and moon, and all the heavenly bodies, thus:- "If [said he] these bodies had power of their own, they would certainly take care of their own regular motions; but since they do not preserve such regularity, they made it plain, that in so far as they co-operate to our advantage, they do it not of their own abilities, but as they are subservient to Him that commands them; to whom alone we ought justly to offer our honour and thanksgiving." (Ibid.)
It was this very teaching which according to Josephus, was a contributing factor in Abraham's decision to leave Ur: "For which doctrines, when the Chaldeans and other people of Mesopotamia raised a tumult against him, he thought fit to leave that country; and at the command, and by the assistance of God, he came and lived in the land of Canaan." (Ibid.)
The belief that Saturday must be the Sabbath of the Bible (because the Jews worship on that day) is an assumption that all Christians have made. However, in light of the fact that the Jews themselves admit that their modern calendar is not the same as that used before the 4th century C.E., Bible scholars and all who love the Sabbath would do well to reexamine this long-held belief. If it is important to worship on a precise, specific day, than the calendar by which you calculate that day must also be the correct calendar. The luni-solar calendar is the only calendar which has roots in the Bible. It was established by God at Creation. All other calendars have roots in paganism. To truly keep the fourth commandment, the Sabbath should be calculated by God's calendar: the moon.
And then the moon, ever punctual to mark the times, an everlasting sign: It is the moon that signals the feasts, a luminary that wanes after being full. The month derives its name from hers. She waxes wonderfully in her phases, banner of the hosts on high, shining in the vault of heaven." (Ecclesiasticus 43:6-8, c.a. 190-180 B.C.)