The Hebrew Calendar and Measure of Time

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June 12th, 2020
Holidays, Teachings / By

Why don’t Jews and Christians celebrate shared holidays on the same day?

There are several Christian holidays that famously correspond with Jewish ones. We know Jesus had a Passover meal with His disciples, which later became known as the Last Supper on the night before His crucifixion. You may also remember that the Outpouring of the Holy Spirit happened on the holiday of Pentecost, which not everyone knows is a Jewish Feast of Weeks, Shavuot.

Shavuot is celebrated 50 days after the first day of Passover. The Christian Pentecost is 50 days after Good Friday, the day of crucifixion. So then, since we’re all counting 50 days from Passover to Pentecost, how come we don’t celebrate both holidays on the same day today?


The Hebraic measure of time is slightly different from the commonly used Gregorian calendar. In short, the Gregorian calendar is solar, which means the seasons are determined by the sun. According to the Gregorian calendar we are now in year 2020, and our year began in January. 

Hebraic calendar is lunar, which means each month is determined by the phases of the moon. Biblically, it would begin in early Spring, when God said the month of Passover would be the first month of the year. However, in today’s Israel, the year starts in early Fall, on the Feast of Trumpets (Rosh HaShanah – head of the year). 

But there is more. It is not just the count of the years that differ between the Judaic and Christian traditions. How do we look at any measure of time – day, week, month? 


In the Hebrew calendar, a day runs from one sunset to the next. This definition is rooted in the Biblical description of the Yom Kippur holiday in Leviticus 23:32, where it says the holiday lasted “from evening to evening”. This understanding is respected still in modern day Israel. 

That is why the holiest day of the week – the Sabbath – rightfully identified as Saturday, starts being celebrated on Friday evening.

Thus, following the same rule, it is common for the Israeli government to do press conferences already on Saturday evening. That is because as soon as the sun sets on Saturday, the new week has begun. 


When God created the world, He did so in six days. On the sixth day, God created man and woman, and instructed them to cultivate the earth.

However, before they even got a chance to rule over creation, there came day number seven – the Sabbath. Adam and Eve started their lives with fellowship with their Creator. 

Because of the story of creation, in Hebrew the days of the week are simply called: Day First (Sunday), Day Second, and so on – ending with Shabbat, the seventh day.

Whenever Western cultures debate whether the week starts on Sunday or Monday, in Israel it’s not even question, because Sunday is literally called Yom Rishon – Day First.


As already shown above, the Bible is quite specific in counting the days, months and years. For every holiday, God chose a specific time in His calendar.

But more than that, God instructed the Israelites also to be mindful when every month begins! 

Rosh Hodesh, meaning the head of the month, corelates with new moon and is a holiday at the beginning of every month. Throughout history, observing the moon helped the Jewish people recognize the appointed times commanded by the Lord. Thus, watching the night sky and celebrating the new moon was a way of keeping track of every passing month. 


Counting the years according to the Hebrew calendar is a slightly complicated process. The leap years in Israel do not have an additional day, but an additional month! Additionally, leap years occur seven times in a 19-years cycle. The additional month is called the second Adar, so some Jews celebrate the holiday of Purim twice, since it’s celebrated during the regular month of Adar. 

Every seventh year is a Sabbath Year (Shmita) when parts of the land are to lie fallow, according to an agricultural rotation. Additionally, at the end of seven cycles of the Shmita Year starts the Year of Jubilee, when according to the Bible slaves were freed and debts were forgiven. 


It is fascinating and exciting to explore this different approach to time and counting our days.

God revealed in His Word that even though He mysteriously works outside of our timeframe, He works with it for our benefit, and wants us to be mindful of it. He teaches us to remain watchful. 

In one of his psalms, Moses expresses it beautifully, asking the Lord: “Teach us to number our days, that we may gain a heart of wisdom.” (Ps 90:12) Whichever calendar we follow, God is teaching us about His appointed times, so we can celebrate the miracles He has done and prepare for the second coming of His Son to Earth. 

Let’s trust the Lord today and worship Him for the miracles that He has done and will continue to do!

Estera Wieja
Estera Wieja is a journalist, book author and public speaker, focused on the topics of Israel, Jewish history, and Judeo-Christian culture. Born and raised in Poland, Estera is a regular contributor to "Our Inspirations" magazine in Poland. She holds a Bachelor degree in Communications and Media from Azusa Pacific University (California, USA), and a Master degree in Journalism from University of Warsaw, Poland. Estera has lived in Jerusalem, Israel for several years before joining the staff at FIRM in 2018.
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