Three evangelists report about the disciples' question asked on the Mount of Olives: When should the consummation happen?
St. Augustine says that these passages are exact parallels and must not be read in antagonism with each other:
Chapter 77. Of the Harmony Subsisting Between the Three Evangelists in Their Narratives of the Discourse Which He Delivered on the Mount of Olives, When the Disciples Asked When the Consummation Should Happen.
147. [...] We have now, therefore, to examine this lengthened discourse as it meets us in the three evangelists, Matthew, Mark, and Luke. For they all introduce it in their narratives, and that, too, in the same order. Here, as elsewhere, each of these writers gives some matters which are peculiar to himself, in which, nevertheless, we have not to apprehend any suspicion of inconsistency. But what we have to make sure of is the proof that, in those passages which are exact parallels, they are nowhere to be regarded as in antagonism with each other. For if anything bearing the appearance of a contradiction meets us here, the simple affirmation that it is something wholly distinct, and uttered by the Lord in similar terms indeed, but on a totally different occasion, cannot be deemed a legitimate mode of explanation in a case like this, where the narrative, as given by all the three evangelists, moves in the same connection at once of subjects and of dates.
With respect to the question concerning the final consummation one finds
Mt: Quod signum consummationis saeculi?
Mc: Quod signum erit, quando haec omnia incipient consummari?
Lk: Quod signum cum fieri incipient?
Mt: What shall be the sign of the consummation of the age?
Mc: What shall be the sign when all this begins to be consummated/fulfilled?
Lk: What shall be the sign when all this begins to come to pass?
Luke 13:3 relates that Our Lord was asked by Peter, James, John, and Andrew. Following the instructions given by Augustine, we can assert that the consummation of the age
corresponds to the fulfillment of all this
, i.e. a series of announced events coming to pass. The question ask for the sign signalling the beginning of
the events constituting the consummation
When do the announced events begin to come to pass?
148. Again, what Matthew states in this form, "And this gospel of the kingdom shall be preached in all the world for a witness unto all nations, and then shall the consummation come," is given also in the same connection by Mark in the following manner: "And the gospel must first be published among all nations." Mark has not added the words, "and then shall the consummation come;" but he indicates what they express, when he uses the phrase "first" in the sentence, "And the gospel must first be published among all nations." For they had asked Him about the end. And therefore, when He addresses them thus, "The gospel must first be published among all nations," the term "first" clearly suggests the idea of something to be done before the consummation should come.
The announced events coming to pass during the consummation are those events mentioned by our Lord after he says et tunc veniet consummatio
(Mt 24:14, and then shall the consummation come). The consummation begins, when we see the abomination of desolation in the holy place (Mt 24:15), after the gospel has been preached among all nations (Mt 24:14).
Luke summarizes what this consummation is about: For these are the days of vengeance, that all things may be fulfilled, that are written.
The consummation of the age
is not a point in time or a literal day, but rather a span of time, the time of great tribulation, such as hath not been from the beginning of the world until now, neither shall be
(Mt 24:21) as announced in (Dan 12:1), a span of time during which false prophet's try to deceive (if possible) even the elect
References:The Harmony of the Gospels, Book II, Chapter 77De Consensu Evangelistarum, Libri Quatour, Liber Secundusdrbo.org