Why do we have the Lord's Supper on the first day of the week?
The New Testament accounts of the institution of the Lord's Supper are found in Matt. 26:26-29; Mk. 14:22-25; and Luke 22:19-20. Paul also cites this occurrence in I Cor. 11:23-26. In all of these, the followers of Christ are commanded to observe the Lord's Supper. Those who constitute a congregation or local church are taught to assemble together for this observance (I Cor. 11:18, 20, 33). In Acts 20:7 we have the example of the church in Troas assembling together "upon the first day of the week" for the purpose of eating the Lord's Supper (called "breaking bread," just as it is in Acts 2:42). This approved example is the only New Testament clue we have as to when first century Christians observed the memorial feast of the Lord's Supper. Church histories compiled by men confirm that it was indeed the practice of Christians in the first few centuries to assemble on the first day of each week for the purpose of eating the Lord's Supper. In later years, led by those who believe that the frequency of doing so and the day of the week upon which it is done are not important, the practice of annual, quarterly, and monthly observances were begun. There is no Bible authority for such.