The order of Communion in Luke 22:17-20 versus Mark 14:22-25 and Matthew 26:26-29

As is usually the case, Matthew closely follows Mark (see note), but in this case Luke varies the account, not only by introducing an additional reference to the cup, but also in other ways that can explain this variance. The author of Luke was aware of the sequence in Mark but wanted to elaborate on Jesus' premonition that one of those present would betray him.

In Mark, the following account appears before the words of the Eucharist Institution:

Mark 14:18-20: And as they sat and did eat, Jesus said, Verily I say unto you, One of you which eateth with me shall betray me. And they began to be sorrowful, and to say unto him one by one, Is it I? and another said, Is it I? And he answered and said unto them, It is one of the twelve, that dippeth with me in the dish.

Again in Mark, when Jesus takes the cup, he gives thanks and goes on to mention of his impending death:

Mark 14:23-25: And he took the cup, and when he had given thanks, he gave it to them: and they all drank of it. And he said unto them, This is my blood of the new testament, which is shed for many. Verily I say unto you, I will drink no more of the fruit of the vine, until that day that I drink it new in the kingdom of God.

The author of Luke wanted to keep both of these important sayings but wanted to expand on the discussion of which apostle would betray Jesus, by linking it to an argument among them as to which would be greatest and then, from this, to Jesus' discourse in which he contrasts the disciples to kings and servants:

Luke 22:23-26: And they began to enquire among themselves, which of them it was that should do this thing. And there was also a strife among them, which of them should be accounted the greatest. And he said unto them, The kings of the Gentiles exercise lordship over them; and they that exercise authority upon them are called benefactors. But ye shall not be so: but he that is greatest among you, let him be as the younger; and he that is chief, as he that doth serve.

This meant that Jesus must mention the cup two times, once before before the words of the Eucharist Institution and once after. It was not feasible to insert Luke's additions before the Eucharist Institution without disrupting the flow, thereby dictating that Jesus premonition of his own death needed to be moved to a position before the Eucharist Institution:

Luke 22:17-18: And he took the cup, and gave thanks, and said, Take this, and divide it among yourselves: For I say unto you, I will not drink of the fruit of the vine, until the kingdom of God shall come.

Footnote: Adam Winn, The Purpose of Mark's Gospel, page 1, says the theory of Markan priority is one of the few that has reached a high level of consensus among New Testament interpreters.

The Marcan-Matthean tradition and the (earlier) Pauline-Lucan tradition vary in how they record the institution of the Eucharist. Compare the reading from Mark and Matthew with Luke and Paul, where Paul records the institution of the Eucharist in 1 Corinthians 11:23-25:

23 For I received from the Lord what I also delivered to you, that the Lord Jesus on the night when he was betrayed took bread, 24 and when he had given thanks, he broke it, and said, "This is my body which is broken for you. Do this in remembrance of me." 25 In the same way also the chalice, after supper, saying, "This chalice is the new covenant in my blood. Do this, as often as you drink it, in remembrance of me."

I bring this up because you will note that both Mark and Matthew record the institution of the Eucharist while they were eating. In contrast, neither Luke nor Paul are entirely clear as to whether Jesus ate at all. Regardless, both Luke and Paul are very careful to point out that the eucharistic cup is instituted after the meal had concluded (μετα το δειπνησαι, 'after they had eaten'). Luke identifies this meal as the Passover (Luke 22:15). Luke's mention of another cup is consonant with Jewish custom during Passover (which included more than just one cup during the ceremony), but the intercalation of two cups surrounding the breaking of the bread highlights that particular action as theologically significant. Indeed, we will see that later on, in the Acts of the Apostles, Luke will use the term 'breaking of the bread' to reference the entire Eucharistic feast (cf. Acts 2:42 & 20:7).

I think the simplest explanation is simply that the Evangelists had slightly different recollections of events. The Church Fathers recognized that there were inconsistencies in the Gospel accounts and accepted them. John Chrysostom discussed this the first of his Homilies on the Gospel According to Matthew, written in the late 4th century:

And why can it have been, that when there were so many disciples, two write only from among the apostles, and two from among their followers? (For one that was a disciple of Paul, and another of Peter, together with Matthew and John, wrote the Gospels.) It was because they did nothing for vainglory, but all things for use.

“What then? Was not one evangelist sufficient to tell all?” One indeed was sufficient; but if there be four that write, not at the same times, nor in the same places, neither after having met together, and conversed one with another, and then they speak all things as it were out of one mouth, this becomes a very great demonstration of the truth.

“But the contrary,” it may be said, “hath come to pass, for in many places they are convicted of discordance.” Nay, this very thing is a very great evidence of their truth. For if they had agreed in all things exactly even to time, and place, and to the very words, none of our enemies would have believed but that they had met together, and had written what they wrote by some human compact; because such entire agreement as this cometh not of simplicity. But now even that discordance which seems to exist in little matters delivers them from all suspicion, and speaks clearly in behalf of the character of the writers.

But if there be anything touching times or places, which they have related differently, this nothing injures the truth of what they have said. And these things too, so far as God shall enable us, we will endeavor, as we proceed, to point out; requiring you, together with what we have mentioned, to observe, that in the chief heads, those which constitute our life and furnish out3 our doctrine, nowhere is any of them found to have disagreed, no not ever so little.