This year Easter is celebrated after Passover, but why? In order to understand why this is happening, we need to look at how the holiday was established and changes that have occurred in history that contributed to these holidays being celebrated a month apart this year.
After coming out of Egypt, God established a new calendar for the children of Israel.
Now the Lord spoke to Moses and Aaron in the land of Egypt, saying, 2 “This month shall be your beginning of months; it shall be the first month of the year to you.
4 On this day you are going out, in the month Abib.
The month of Abib, later renamed Nisan, occurs in the spring. The events immediately surrounding the establishing of this new calendar is the first Passover. Passover was ordained by God in Leviticus 23, along with the Sabbath and six other biblical holy days (feasts). Four of seven biblical holy days take place in the spring or early summer; the last three take place in the fall. On the first Passover, Nisan 14, God delivered the children of Israel out of bondage in Egypt.
Fast-forward to the first century. When Jesus was 12 years old, He and His family traveled to Jerusalem to celebrate Passover. Scripture tells us that Jesus continued to celebrate Passover as an adult. On the last Passover of Jesus’s life, He died for us!
After the death of Jesus, new believers not only celebrated Passover, but also celebrated the resurrection of Jesus, the Messiah. Although the early church continued to celebrate Passover, things changed in the third century.
After the death of Jesus, new believers continued to celebrate Passover but now they also celebrated their deliverance from sin and new life in Jesus the Messiah. The early church began a sect within Judaism, and it consisted mainly of Jewish believers. By the end of the first century, many Gentiles had joined Jewish believers in the early church. It did not take long for schisms to form for many religious and political reasons. By the third century, Judaism and Christianity were viewed as two separate religions.
However, many early Christians still celebrated both Passover and the Resurrection, but on different days. At the Council of Nicea in 325 AD it was ruled that the Resurrection would be celebrated on the first Sunday following the full moon after the spring equinox. The calendar used at this time was the Julian calendar and the date on this calendar for Easter was set for March 21. The name Easter is likely a transliteration of the word Passover.
In 1582 the modern calendar, the Gregorian calendar, was adopted. This caused problems for dating Easter.
The Eastern Church continues to use the Julian calendar and they will celebrate Easter on April 8th.
Protestant and Catholic churches celebrate Easter on the first Sunday after the first full moon, after the vernal equinox, unless that date is a Sunday, then the date is delayed one week. This year the Protestants and Catholics will celebrate Easter on April 1st.
Jewish Passover: On the biblical calendar, Passover is on March 30th.
In the two millennium since the death of Jesus, believers have gone from celebrating Passover and the Resurrection within days of each other to celebrating them based on differing calendars. This year, our family will be celebrating the Resurrection with our fellow believers in April. But in March, we will come together to celebrate the first Passover and remind ourselves of that fact that Jesus is the final Passover lamb that was slain for us.
East and West
When the Church separated into Eastern and Western groups, the date for celebrating Easter differed.
When Jesus came, significant events occurred on each of these holy days:
Passover: Jesus died.
Feast of Unleavened Bread: Jesus was buried.
Feast of First Fruits: Jesus rose from the dead!
Pentecost: The Holy Spirit was given to the Church.
Ancient civilizations measured time with a variety of calendars. While each was different, they used primarily a solar, lunar, or lunisolar approach.
The solar approach meant their calendars were set based on the revolution of the earth around the sun. The Egyptian calendar would be an example of an ancient civilization that used a solar calendar.
The lunar approach measures time using the phases of the moon. The Sumerian’s used a lunar calendar.
The lunisolar approach set their calendar to acknowledge both the phases of the moon and the solar year. The biblical calendar would be an example of a lunisolar calendar. The years are based on the solar year, but the months are based on the phases of the moon.
The Julian calendar was introduced to the Roman Empire in 46 BC. As Rome began to conqueror the world, Julius Caesar ordered a new calendar to be developed that would better follow the solar year. This calendar is named for him. The Julian calendar is still in used by the Eastern Orthodox churches to set the holidays. This calendar was the used for centuries.
The Gregorian calendar, sometimes referred to as the Christian calendar, was introduced in 1582. Under Pope Gregory XIII the Julian calendar was revised. Revisions included adding a leap year every fourth year and changing how the holiday of Easter is determined. Today, the Gregorian calendar is used throughout the world.
Eastern Church and Western Church
On the biblical or Hebrew calendar, the months begin with the new moon, so twelve months only equal a 360-day year. To compensate for this short year, an additional month is added 7 times in every 19 years cycle. (source)