Suppose we accept as a working hypothesis (for the sake of argument) that Matthew was written prior to Mark (and prior to Luke). Mark’s Gospel does not have the Lord’s prayer. However, if Mark really is written, as Clement of Alexandria tells us, as a Gospel account whose form is intended to conform to the early Christian practice of ‘the secret’ (the practice of not divulging liturgical elements of the faith to the uninitiated), and if the Lord’s prayer were central to the early Christian liturgy, then it would make sense for Mark to exclude the Lord’s Prayer from his Gospel. Note that most scholars recognize that because both Matthew and Luke contain the Lord’s prayer, it likely belonged to the Q source, and on the hypothesis that there was a Q source the Lord’s prayer was known and recited in at least some Christian communities prior to Mark. So, plausibly, the Markan community (or Mark) was aware of the prayer (though it would also be plausible that the Markan community, or Mark, had not heard of the prayer – but I can see no theological reasons for a Markan exclusion of the prayer). So, on the hypothesis that Matthew antecedes Mark, the reason Mark leaves out the Lord’s Prayer is just that it is at the very center of the Christian Liturgy (it appears in the Didache, for example).
One might then raise a quandary about the fact that the prayer in Matthew, supposedly prior to the form it takes in Luke, is significantly more elaborate. To see this, I’ve put Matthew’s version followed by Luke’s, and I’ve highlighted the differences by ‘red letters’.
‘Pray then in this way:
Our Father in heaven,
hallowed be your name.
Your kingdom come.
Your will be done,
on earth as it is in heaven.
Give us this day our daily bread.
And forgive us our debts,
as we also have forgiven our debtors.
And do not bring us to the time of trial,
but rescue us from the evil one.
He said to them, ‘When you pray, say:
Father, hallowed be your name.
Your kingdom come.
Give us each day our daily bread.
And forgive us our sins,
for we ourselves forgive everyone indebted to us.
And do not bring us to the time of trial.’
Why is Luke’s version so much more modest? You would think if it came later then, if anything, it would have been embellished. The first thing to note here is that even on the standard hypothesis Luke comes after Matthew, and it isn’t unlikely that Luke was familiar with Matthew (though some scholars argue that Luke couldn’t have been familiar with Matthew precisely because of oddities like this apparent shortening of the Lord’s prayer, which is best explained, they think, by appealing to a source common to both Matthew and Luke, namely Q). However, colour me conservative, but it seems that a much more obvious answer can be given for why Luke’s version differs from Matthew’s. As Herbert Thurston explains:
As for the prayer itself the version in St. Luke 11:2-4, given by Christ in answer to the request of His disciples, differs in some minor details from the form which St. Matthew (6:9-15) introduces in the middle of the Sermon on the Mount, but there is clearly no reason why these two occasions should be regarded as identical. It would be almost inevitable that if Christ had taught this prayer to His disciples He should have repeated it more than once. It seems probable, from the form in which the Our Father appears in the “Didache”, that the version in St. Matthew was that which the Church adopted from the beginning for liturgical purposes.
~The Lord’s Prayer
Here’s how the Lord’s Prayer appears in the Didache:
Neither pray ye as the hypocrites, but as the Lord commanded in His Gospel,thus pray ye:
Our Father, which art in heaven,
hallowed be Thy name;
Thy kingdom come;
Thy will be done,
as in heaven, so also on earth;
give us this day our daily bread;
and forgive us our debt,
as we forgive our debtors;
and lead us not into temptation,
but deliver us from the evil one;
for Thine is the power and the glory for ever and ever.
There is no good reason to doubt that the Church used St. Matthew’s longer account of the prayer for the Liturgy from the beginning. In fact, it is supported by some Patristic evidence even beyond the Didache. For instance, it makes sense of an otherwise odd fact about Jerome; namely “that he changed the pre-existing word quotidianum into supersubstantialem in St. Matthew but left quotidianum in St. Luke” (Thurston). The supersubstantialem obviously carries more theological-liturgical baggage as a translation of the Greek ἐπιούσιον. On the hypothesis that Matthew did precede Luke, given that Matthew’s version is much more formal, it could be that the earliest Christian communities not only adopted it as the formal prayer as a matter of convenience or preference, but that they recognized Matthew’s version to be a record of the authoritative version for the Christian liturgy. We’ve already seen how, in the Didache, the form of the Lord’s prayer is Matthean, so we know that the earliest Christian liturgies we can get a hold of (plausibly as early as the 50’s A.D.) the formula which appears in Matthew’s Gospel is the one which appears in the celebration of the liturgy. Moreover, that the Lord’s Prayer (in its Matthean form) was considered essential for the liturgy by the Church Fathers can be demonstrated by a mere survey. For instance, St. Pope Gregory the Great wrote:
“But the Lord’s prayer (orationem Dominicam) we say immediately after the prayer (mox post precem) for this reason, that it was the custom of the apostles to consecrate the host of oblationto (ad) that same prayer only. And it seemed to me very unsuitable that we should say over the oblation a prayer which a scholastic had composed, and should not say the very prayer which our Redeemer composed over His body and blood .”
~Gregory the Great, Registrum Epistolarum, Book ix, letter 12
There can be no question that the form of the prayer Pope Gregory had in mind was the Matthean one. This indicates that the ‘our Father’ was not only recited in the liturgy from the beginning, but that it is part of the form of the Eucharistic prayer (all Sacraments have matter and form). St. Jerome can be cited to the same effect (again from Thurston): “St. Jerome asserted (Adv. Pelag., iii, 15) that “our Lord Himself taught His disciples that daily in the Sacrifice of His Body they should make bold to say ‘Our Father’…” Again, there can be no doubt that Jerome had the Matthean version in mind.
So, Matthew includes the proper liturgical form (or at least includes the version which, from the earliest time, was adopted as the proper liturgical form) given during the sermon on the mount, Mark practices the secret in not including the prayer at all, and Luke seems to practice the secret by going out of his way to cite an informal version of the prayer repeated by the Lord at some time other than at the sermon on the mount (note that what Luke calls the sermon on the plain is one which, I think, is not in fact the same as the sermon on the mount). There is no evidence of any early ‘Lukan’ community celebrating the Liturgy using an abbreviated form of the Lord’s prayer (or any early ‘Q’ community celebrating with a shorter form – though that’s also because there just isn’t any evidence of any early ‘Q’ community).