The phrase this generation occurs sixteen times in the New Covenant scriptures. The problem is that scholars don’t agree on how we should understand the term, especially at Matthew 24:34, where we are told that this generation shall not pass until all these things (i.e. the things Jesus described in Matthew 24:4-33) occur. Some scholars conclude this generation refers to the race of the Jews, meaning there will always be a Jewish people until the time of Jesus’ second coming. Nevertheless, the word is never used in this sense in the whole of the New Covenant record. Other scholars conclude that this generation refers to the final generation before the end of the world. However, such a conclusion hardly honors Jesus’ standing as a prophet, because, if there could be an end to the world, there **must** be a final generation that wouldn’t pass until the end occurred. So, how should we understand this phrase?
The easy solution of the problem would be to go to the New Covenant scriptures and see how Jesus and his disciples used the word generation. If the context of their words is clearly understood, then sola scriptura demands that we take the understanding of what we read. Anything other than the clear words of the Bible would be nothing more than the opinion of men, and a wrong understanding at that.
An extra-biblical source defines generation as: “all the people of about the same age within a society or within a particular family, or the usual period of time from a person’s birth to the birth of his or her children” (The Cambridge Dictionary). Admittedly, this definition is not proof of how Jesus or his disciples used the word, but as we shall find in the scriptures, this is exactly how they used the word generation.
In the very first chapter of the New Covenant record we find that Matthew uses the term to indicate about 30 to 40 years. Notice how he used the word in the conclusion of Jesus’ genealogy through Joseph:
So all the generations from Abraham to David are fourteen generations; and from David until the carrying away into Babylon are fourteen generations; and from the carrying away into Babylon unto Christ are fourteen generations.(Matthew 1:17 KJV)
Obviously, Matthew isn’t speaking of 42 races in this verse. Therefore, we must conclude generation is understood exactly as defined by the Cambridge dictionary, quoted above, Abraham begat Isaac and Isaac begat Jacob etc. That is, a generation is that “period of time from a person’s birth to the birth of his or her children.” If Abraham was born in the second millennium BC (cir. 1900 BC), and there are 40-42 generations in Jesus’ genealogy (David and Jeconiah are used twice) then a generation would equal 45 to 47 years. If we factor in the longer lives of the patriarchs and the much shorter lives of some of the kings of Judah, we could no doubt round off a generation to equal about 40 years, and this is the time figure the scriptures seem to use as a generation (Hebrews 3:7-10).
 The phrase this generation occurs at Matthew 11:16; 12:41-42; 23:36; 24:34; Mark 8:12 (twice); 13:30; Luke 7:31; 11:30, 31, 32, 11:50-51; 17:25; 21:32. The word generation is used with the words evil, adulterous, sinful or wicked at Matthew 12:39, 12:45; 16:4; Mark 8:38 and Luke 11:29. The word generation is used with the words faithless and perverse at Matthew 17:17; Mark 9:19 and Luke 9:41. Finally, the word generation is used with the word untoward at Acts 2:40 (all references are from the KJV).
 Of the Biblical works available to me, see Henry Alford’s New Testament Commentary, Peoples New Testament, Popular Commentary by Philip Schaff, and Adam Clarke’s Commentary.
 Of the Biblical works available to me, see John Trapp’s Complete Commentary and The Expository Notes of Dr. Constable.