Sunday in Armenian is called Kiraki. In early times Sunday was called Miashabat, or the first day of the week. Since Christ resurrected on Sunday, the day obtained a new meaning for Christians and was renamed to Kiraki (Kyriaki), or Lord’s day in Greek. For the followers of Christ, the day which kick-starts the week has forever been linked to the Lord, gaining special reverence and importance. On this day Christ resurrected the fallen nature of man, delivering it from death by sin. Shortly after, on the day of Pentecost (another Sunday), another important event happened – Holy Spirit descended, renewing those who were present, and they tasted the bounties of heavenly life. A day that was ordinary before became a day of enormous significance, an important precursor of the life to come. Hence, the Church declared Sunday to be a day of cessation from daily chores and a day of dedication to the Lord, thus replacing the following of Sabbath in Old Testament with rest of Sunday.
In the early days of Christianity Liturgy was conducted by Apostles themselves at Agapes or devotional congregations, during which they (and later their ordainees) administered Christ’s body and blood to the faithful. This later expanded and evolved into the formal rites of Divine Liturgy.
By the teachings of Church fathers, the second coming of Christ will also occur on Sunday, when all reposed will rise and face the Righteous Judge.