In the early Christian times, Easter was associated with the older Jewish feast of the Passover.
Passover was celebrated to commemorate the Exodus of the Jews from Egypt, where they were suffering under slavery.
"The Jews asked their Lord to help to free them and were told to celebrate the upcoming departure from Egypt
on the 14th day of the lunar month of Nisan (which roughly corresponds with the latter part of March and the first
part of April) by choosing a year old lamb without blemish, sacrificing it, and smearing the doorposts and lintels of
their houses with its blood. The lamb was to be roasted on fire and eaten with unleavened bread and bitter herbs.
On the following night a destroying angel passed over Egypt, killing all the first-born in every house, except in
those marked with the blood of lamb. After this, the pharaoh of Egypt hastened the Jews to leave his country, fearing
otherwise all his people would be killed. Since then the Jews celebrated every year to commemorate their Exodus
from Egypt. This feast is called Passover Pesach."
Passover reminded the Jews, that like the blood of an innocent lamb saved the lives of their first-born in Egypt,
so is their Messiah to shed his blood over the sins of man and save him from eternal death.