Coptic.net gives the following explanation:
“The Liturgy according to St. Basil is the one used most of the year;
St. Gregory's Liturgy is used during the feasts and on certain occasions;
only parts of St. Cyril's Liturgy are used nowadays.”
They also mention the following:
“It is worth noting here that the Liturgy was first used (orally) in Alexandria by St. Mark and that it was recorded in writing by St. Cyril I, the 24th Patriarch of the Coptic Orthodox Church of Egypt.
This is the Liturgy known as St. Cyril's Liturgy and from which the other two liturgies -- referred to above -- are derived.”
My question is:
If the St. Basil and St Gregory liturgies came from St. Cyril - why not just use St. Cyril’s liturgy all the time? It’s literally the liturgy that St. Mark used himself ... so why don’t we pray it that often?
1- We don’t know what liturgy Saint Mark prayed during his time in Alexandria. Certainly he handed down a way of celebrating the Eucharist. At his time, bishops had the liberty to improvise their own prayers of thanksgiving to accompany the actions of Eucharistic rites. As such, there is no way to affirm that Saint Mark prayed the liturgy attributed to him, especially in the absence of textual evidence from that time. The earliest textual witnesses to fragments of an anaphora resembling what we know today as Saint Mark/Cyril in Greek are from the 4th/5th century.
2- Nothing is known with certainty about the role played by Saint Cyril in expanding, codifying, or anything else to the liturgy of Saint Mark. Attributions to him appear in the Copto-Arabic tradition in the Middle Ages. It’s only a tradition in the Coptic Church, while the Greek Orthodox Church of Alexandria has no such tradition. It’s common to attribute things to major local church figures. For example, the liturgy of St. John Chrysostom was almost certainly not written by him. Yet, as an important patriarch of Constantinople, it was only natural to honor him posthumously by attributing the local anaphora to him.
3- The liturgies of Saint Basil and Gregory have nothing to do with saint Cyril. They are quite ancient themselves and follow the so-called Antiochene structure that Mina described. The idea that other liturgies came from Cyril (or the the liturgy of James, as has been claimed too) is an outdated and common claim, based on the assumption that there was one ancient universal liturgy from which all the rest descended. To state it very briefly, this theory has no basis and is largely discredited now.