The answer
The Oriental and Eastern Orthodox Churches follow the Jewish lunar system and celebrate the Holy Resurrection Feast after the Jewish Passover. The Catholic and Protestant Churches use a system by which the Resurrection Feast is celebrated on the first Sunday following the first full moon after the vernal [spring] equinox.Your friends will benefit much more by learning and reading deeper about our Church:
https://suscopts.org/resources/literature/orthodox-faith/.
Answered by His Eminence Metropolitan Youssef (opens in a new tab)