En Theos

When and why was Sunday designated a day of rest?

Before Sunday was designated as a day of rest by the emperor Constantine in the fourth century, it was already a special day in the life of Christian communities. Sunday had become a distinctive day because of its association with the day on which Jesus rose from the dead. Celebrating that day by gathering and remembering what Jesus had done for all humanity seemed natural and appropriate.
The first account of Sunday gatherings comes from Justin Martyr in his "Apology," written around the year 150. Justin explains why Christians assemble on Sunday: "We gather on the day of the sun because it is the first day, when God transformed darkness and matter and made the world; on this same day Jesus Christ, our Savior, rose from the dead." It seems obvious that this practice was already well established by Justin's time.
From earliest times, every Sunday was and is still understood to be a celebration of Easter and of the entire paschal mystery. From the time of Constantine when Christianity became the dominant religion, Sunday became a day of rest for all. This day was to be used to connect more deeply with God and one another through prayer, reflection, communal gatherings and acts of kindness and mercy, especially towards those in need. Sunday was to be the day in which Christians re-created themselves into what God had intended from the beginning.