The biblical law to count weeks, while Jews count days
The ancient religious Jewish group called Pharisees, who existed from about 320 BCE until 70 CE, and the rabbis who followed them changed all of the biblical holidays and practices in some ways. Let’s look at the law mandating counting, called in Hebrew Sefirat Ha’Omer, and the holiday of Shavuot.
Leviticus 23 speaks about the holiday “Passover” on the fourteenth day of the first month and the seven day holiday “The Feast of Unleavened Bread” that begins on the fifteenth day. In 23:15 and 23:16 the Torah states: “You should count from the day after the Sabbath, from the day that you brought the Omer that is waived [a weight of barley grain]; seven weeks; they should be complete [weeks]; until the day after the seventh Sabbath, you should count fifty days” [when an offering is brought in the temple of the newly harvested wheat grain as a Thanksgiving offering to God for the harvest – emphasis added]. The fiftieth day is called Shavuot, or “weeks,” because it concludes the seven full weeks of seven days each from “the Sabbath.”
The plain sense of this command is that the Israelites should observe the celebration of the harvest on the day after the Sabbath which occurs seven full weeks after the Sunday following the holiday of Passover. The reckoning begins on a Sunday and Shavuot is to be observed on a Sunday. In essence, the holiday has no significance in the Bible other than being the end of seven weeks and being a harvest festival. The word “Sabbath,” used twice in the command is the seventh day; “they shall be complete [weeks]” is seven days from Sunday through Saturday, the usual understanding of a complete week; and the command to count does not require a verbal counting, just as a verbal counting is not required when the Torah states that a menstruate “must count seven clean [bloodless] days” before becoming clean (Leviticus 15:28) and the Israelites didn’t have to physically “count seven cycles of Sabbatical years” until the Jubilee year (Leviticus 25:8). It is also no surprise that the Bible was unable to set a date when Shavuot would occur since the date of the Sunday when the count began varied from year to year.
However, the Pharisees and their successors the rabbis changed this. They created a new, non-biblical law requiring Jews to verbally count each day between Passover and Shavuot and even say a blessing before each count. Most significantly, they translated Sabbath as the first day of Chag Hamatzot and began the count on 16 Nissan. Now that the count began on a specific day and not the Sunday after the holiday ended, the rabbis were able to establish the sixth day of the month Sivan as the date of Shavuot. The rabbis also gave an entirely new significance to Shavuot, saying it commemorated the season when the Torah was revealed to the Israelites.
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Why did the Pharisees and rabbis require Jews to count verbally? Who were the Pharisees? Why did they change the day the count began? Was there opposition to the change? Why did they give Shavuot a new purpose? All of this is explained in another chapter in my book.
 This is a version of a chapter in my new book “Mysteries of Judaism,” in which I point out that every single biblical holiday was changed by the rabbis, Jews today practice Rabbinical Judaism not Torah Judaism, and Christianity therefore did not grow out of Torah Judaism but from rabbinical Judaism.
 Since around the sixth century BCE, while in exile in Babylonia, Jews called the first month by it Babylonian name Nissan.
 Why count seven weeks? Jews used the number seven in over one hundred different ways. For example, the seventh day of the week is called the Sabbath; the first day of the seventh month of the year is called in the Bible Yom Teruah, the day of the blowing of the shofar, a name the rabbis changed to Rosh Hashana, the New Year; the seventh year is the Sabbatical year; the seventh Sabbatical year is the Jubilee Year. What is missing is the seventh month. This is why Scripture mandates counting seven weeks. This is the purpose of Shavuot, “weeks,” It is the end of seven weeks.
 They maintained a rudiment of the biblical command by mentioning not only days but weeks. For example the formula for the 39th day would be “Today is the 39th day, which is five weeks and four days of the [counting of the] Omer.
 Although most people think that the rabbinical use of “the season of the giving of the Torah” should be taken literally, meaning this was approximately when the Five Books of Moses was given to the Israelites, this is obviously untrue. The Torah was written over different times, and includes many events during the forty-year desert wanderings and the death of Moses. The word Torah here means the Decalogue, the Ten Commandments. Why did the rabbis say it is the season when the Decalogue was revealed and not the day? Because the Torah does not state the day of the revelation.