The only place that the Bible uses the words “Lord’s Supper” is 1 Corinthians 11:20 1 Corinthians 11:20When you come together therefore into one place, this is not to eat the Lord’s supper.
American King James Version×. Many church organizations today have periodic ceremonies, which they call the Lord’s Supper, assuming that this passage offers this as the official name for partaking of the symbols of bread and “the cup.” However, Paul used the Greek expression kuriakon deipnon (literally, “a lordly meal”) to tell the Corinthians that their shameful conduct at the common meal prior to this ceremony did not constitute a Christian meal. The ceremony Paul wrote about is the Passover, one of the seven annual festivals of God (Leviticus 23). Paul refers to this ancient festival in the same way that Jesus did, as recorded in the Gospels.
While Paul does not directly disallow the term “Lord’s Supper,” neither does he endorse it. Rather he emphasizes that the “tradition” (1 Corinthians 11:2 1 Corinthians 11:2Now I praise you, brothers, that you remember me in all things, and keep the ordinances, as I delivered them to you.
American King James Version×) he received involved only bread and wine, not a supper meal. There is no scriptural instruction to use the term “Lord’s Supper” to refer to the Passover.
Most Christian churches fail to perceive the timeless significance of the Passover and its unbreakable association with the other festivals of God and choose not to include it in their worship. Instead, they follow substitute traditions, including what is variously called “the Lord’s Supper,” “Eucharist” or “Communion.”
Centuries ago, men invented the name “Eucharist,” taking it from the Greek word that means “giving thanks” in a scripture that actually speaks of Christ keeping the Passover (Luke 22:17 Luke 22:17And he took the cup, and gave thanks, and said, Take this, and divide it among yourselves:
American King James Version×, 19). Similarly, some churches appropriate the name “Communion,” from a reference to the Passover (1 Corinthians 10:16-17 1 Corinthians 10:16-17  The cup of blessing which we bless, is it not the communion of the blood of Christ? The bread which we break, is it not the communion of the body of Christ?  For we being many are one bread, and one body: for we are all partakers of that one bread.
American King James Version×).
Because of the scriptural instruction, as well as the example of the early New Testament Church, the United Church of God observes the New Testament Passover, in addition to the other festivals of God. Our booklet God’s Holy Day Plan: The Promise of Hope for All Mankind explains more about this important subject.