The Divine Service on Sunday is the main or primary service of the Christian Church throughout history. It is THE service of worship for Christians. The Divine Service is the Communion Service of the Church.
During the days of the Apostles, Sunday was the day of worship. The reason for this is twofold. First, Christ is the fulfillment of the Law. Everything in it points to Him. Christians are no longer bound to a specific day of the week. Second, Sunday was the day of Christ’s resurrection. The Church celebrated worship on Sundays because each Sunday was Easter.
In those early days of the church, the Divine Service was separated into two services: The Service of the Word and The Service of the Sacrament. The Service of the Word was held in the morning and the Service of the Sacrament was held in the evening. With the Service of the Sacrament, the Church held a potluck type dinner called an Agape Feast or Love Feast. This feast was a community meal, kind of like what churches do today throughout the year.