Synoptic study
If we assume Markan priority, then the uniqueness in Luke takes on added significance. First Luke leaves out the reference to the gathering of the Elect. This may be to place the warning at the end of the discourse, But watch at all times, praying that you may have the strength to escape all these things that will take place, and to stand before the Son of Man. (vs. 36) The burning question is what are “all these things”. It is frustrating for me to understand these eschatologies outside of the dispensational construct I grew up with and have rejected. This could be taken as a support for a pre-trib rapture. But I think that the things referred to are not the supposed Great Tribulation, but the real possibility of falling away during the trials the Jews and the Church would face. Hooker takes a look at the Markan text in the same way:
At the end of the discourse, we have two parables and a number of sayings, which seem to have been linked together because of certain words and phrases that they have in common. The first is a parable about a sign – a natural enough pericope to have added here. Yet it fits badly into its context: these things in v. 29 cannot refer to the events in vv.26f., since they were themselves the climax to the period of waiting. The parable has been added here because it was thought to be on the same theme as the rest of the discourse, but in the setting of Jesus’ own lifetime it may well have had a different emphasis. Even in its present setting, Luke takes it to be a parable about the Kingdom of God, and he may well be right. If so, then perhaps the signs, which showed that the Kingdom was near were originally the activities of Jesus himself (cf. Luke 11.20; 12.54-6). Mark may perhaps have had another reason for adding the parable at this point. The parable is about a fig tree, and it was a fig tree that was cursed in chapter 11, when Jesus first pronounced judgment on the temple and on Israel. It is significant that now, when Jesus has spelt out the nature of Israel’s punishment and the final gathering of the elect, we have a story about another fig tree. The dormant tree, apparently dead, bursts into new life, and its young leaves are a promise of coming summer: hope and not destruction, is the final word….
…Many attempts have been made to understand the Greek for this generation in some other way, but they are all unconvincing. The reason for these attempts was the embarrassment caused by an apparently unfulfilled prediction in the mouth of Jesus. An alternative solution was to limit the application of the phrase ‘all these things’. Once it is recognized that the saying did not originally belong in its present context, the difficulties become rather different. If it is an authentic saying, to what did it originally refer? The similarity with Mark 9.1 suggests that it could have referred to the Kingdom of God. A comparison of that saying with the Matthaean parallel shows how easily a saying about the coming of the Kingdom could be reapplied to the coming of the Son of man. But perhaps it is a warning of unknown origin, couched in traditional apocalyptic language and used here by Mark because it seemed appropriate – at once ominous and vague. Used here, the saying provides an important clue to Mark’s purpose in this chapter. If all these things are to take place within this generation, then we understand why he ends the discourse with the warnings in vv.33-7. The fact that some Christians have been misled by false signs of the parousia does not mean that there is no need for continual vigilance: sooner or later the End will come, and Marks’s readers must therefore keep watch.