For there shall arise false Christs, and false prophets, and shall shew great signs [σημεῖα] and wonders [τέρατα]; insomuch that, if it were possible, they shall deceive the very elect.
-- Matthew 24:24
For false Christs and false prophets shall rise, and shall shew signs and wonders, to seduce, if it were possible, even the elect.
-- Mark 13:22
As detailed below, Luke positively values the signs and wonders of the apostolic age. He certainly doesn't want a Jesus who throws shade on them, especially since it is really "the holy child Jesus" by whose name the signs and wonders are done.
And I will shew wonders in heaven above, and signs in the earth beneath; blood, and fire, and vapour of smoke:
-- Acts 2:19
Ye men of Israel, hear these words; Jesus of Nazareth, a man approved of God among you by miracles [δυνάμεσιν] and wonders and signs, which God did by him in the midst of you, as ye yourselves also know:
-- Acts 2:22
And fear came upon every soul: and many wonders and signs were done by the apostles.
-- Acts 2:43
And now, Lord, behold their threatenings: and grant unto thy servants, that with all boldness they may speak thy word, By stretching forth thine hand to heal; and that signs and wonders may be done by the name of thy holy child Jesus.
-- Acts 4:29f.
And by the hands of the apostles were many signs and wonders wrought among the people; (and they were all with one accord in Solomon's porch.
-- Acts 5:12
And Stephen, full of faith and power, did great wonders and miracles [signs] among the people.
-- Acts 6:8
He brought them out, after that he had shewed wonders and signs in the land of Egypt, and in the Red sea, and in the wilderness forty years.
-- Acts 7:36
Long time therefore abode they speaking boldly in the Lord, which gave testimony unto the word of his grace, and granted signs and wonders to be done by their hands.
-- Acts 14:3
Then all the multitude kept silence, and gave audience to Barnabas and Paul, declaring what miracles [signs] and wonders God had wrought among the Gentiles by them.
-- Acts 15:12
Luke's freedom in eliding entirely the "false Christs" line at a minimum shows that the apocalyptic tradition narrated in Matthew 24, Mark 13, and Luke 21 is not yet fixed in the evangelists' own time as they struggled to reimagine and repurpose the (failed) apocalyptic material of the earlier time of the historical Jesus which lies behind it.
It has long been recognized that this apocalyptic material is a series of independent units more or less successfully woven together into a "composite discourse", but it is a "tangled skein", some elements of which might be editorial by the evangelists, some pre-existing apocalyptic either Jewish or Jewish Christian, some authentically dominical, et cetera. So Vincent Taylor, The Gospel According to St. Mark, London 2nd edition, 1966, 1977, pp. 498ff., who considers Matthew a later version of Mark, but Luke, who has "little linguistic agreement with Mk.", to be a stand alone witness presenting material from "independent" sources who must be reckoned with for the development of apocalyptic but often is not.
As Taylor recognizes, Mark's vocabulary in 13:21f. has the "later ring" of "primitive Christianity" about it. It is an apocalyptic outlook now "strange to the mind of Jesus". So it would not be odd then for Luke to exclude it, concerned as he self-consciously is to lay out his history more accurately than have other evangelists.
What we have in these apocalyptic narratives, including Luke's, is revisionism at work.
The "false Christs" idea reflects later developments, a later Christianity on the way from a Judaism which had its own false prophets, to a later Pauline world populated also by a false gospel (II Cor. 11:4; Gal. 1:6), false apostles (II Cor. 11:13), false angels (II Cor. 11:14), the son of perdition (II Thes. 2:3), and ultimately the Antichrist(s) of I and II John.
The historical Jesus, imagining the imminent end of the world in his own lifetime, would never have imagined such developments by definition.
But Luke himself hasn't thought of such things, of course, nor about the implications for either his Gospel or his Apostle (Acts, primarily about Paul). Luke's aim is to present the signs and wonders characteristic of the early and middle Pauline period as proof of his Gospel.
What is also often not considered enough is that the false Christs language of Matthew 24 and Mark 13 might actually be explicit anti-Pauline propaganda, in which case this calumny might represent the particular trigger, among other deficiencies, which motivated Luke to compose his definitive two-volume work in defense of the real Jesus and his hero Paul as he understands them, in order that his patron Theophilus "may know the certainty of those things" in which he was instructed (Luke 1:4).
