because of differing calendars

However, as discussed above, Eastern Orthodox and Western/Eastern Catholic Easter falls on different dates because of differing calendars.

most Orthodox churches retained some version of the Julian calendar

The Orthodox Easter dates usually differ from the dates used by western churches because most Orthodox churches retained some version of the Julian calendar, which is older than the Gregorian calendar, commonly used today.

on different dates due to differences in the calculation of the date of Easter

Orthodox Easter and Catholic Easter are on different dates due to differences in the calculation of the date of Easter.

from following the julian calendar that differs from the gregorian calendar which is used by most western countries and christian denominations

The different date for Orthodox Easter comes from following the Julian calendar, which differs from the Gregorian calendar used by most western countries and Christian denominations.

on a different day from other Christian denominations

Orthodox Christians celebrate Easter on a different day from other Christian denominations.

on different days

Every year the Orthodox Easter takes place on different days and does not always coincide with a similar holiday in other religions.

on the error of the Julian Calendar

But the difference in the celebration of Easter between Orthodox and Catholics is not only based on the error of the Julian Calendar but also on the error of the so-called “Metonic cycle”, named after Greek astronomer Meton of Athens of the 5th century BC.

at a later date than the Easter date observed by many western churches

The Orthodox Christian date for Easter Sunday often occurs at a later date than the Easter date observed by many western churches.

of Passover

The other difference in the determination of Easter between the Orthodox and other Christian Churches concerns the date of Passover.

Due to the introduction of the Gregorian calendar

Due to the introduction of the Gregorian calendar, Orthodox and Roman Catholic Easter now only coincide once every several years.

on the first Sunday after the first full moon based on the Julian calendar

Orthodox Easter is on the first Sunday after the first full moon based on the Julian calendar, this year being on April 28.