In sending out his disciples and students to teach the message that Jesus was handing down to them, Jesus is warning them about their future persecution at the hands of the Roman and Jewish officials.
He is also discussing the effects of the brewing violence in the decades to come against the Jewish people by the Romans, in what historians refer to as the Jewish-Roman Wars.
During those years, the Romans burned Jewish towns and cities, and murdered millions of Jewish citizens in Jerusalem and the surrounding towns and cities. It was a massacre of massive proportions - during which Jerusalem was burned to the ground - and the Jewish people scrambled to stay alive. This sometimes pitted them against their own family members as the Romans began interrogating people, looking for rebel instigators.
The final point Jesus makes is: "I tell you the truth, you will not finish going through the cities of Israel before the son of man comes.” What does this mean?
Appointed ecclesiastical Christian teachers and their followers (which include those translators of the texts into English) have assumed that Jesus is speaking of his "second coming" - construed as a time somewhere in the distant future when he will return when the end of the world comes and gather all his faithful and bring them to heaven. They usually depict Jesus arriving on the clouds - sometimes on horseback - carrying a big sword to chop everyone's heads off.
This, however, is pure speculation. Jesus never described such an event. And in this conversation, Jesus is speaking specifically to his disciples, as he instructs them to go out and pass on his teachings. He knows that he will soon be departing his body and returning to the spiritual world, and he wants his disciples to continue spreading his teachings. Remember that just before this he says:
"But when they arrest you, do not worry about what to say or how to say it. At that time you will be given what to say, for it will not be you speaking, but the Spirit of your Father speaking through you." (Matt. 10:19-20)
So Jesus is instructing his disciples how to deal with the coming events they will each directly deal with as they speak on God's behalf.
Jesus is not speaking to people thousands of years into the future as some would like to imagine. Just consider how ecclesiastical Christian teachers have incorrectly speculated about their interpretation of the "second coming" of Jesus and impending apocalypse and been wrong over the centuries:
Hilary of Poitiers: 365 AD (the date predicted as the second coming and end of time)
Saint Martin of Tours: 375 to 400 AD
Sextus Julius Africanus: 500 AD
Gerard of Poehlde: 1147 AD
John of Toledo: 1179 AD
Joachim of Fiore: 1205 AD
Pope Innocent III: 1284 AD
Melchior Hoffman: 1533 AD
Benjamin Keach (Baptist): 1689 AD
William Whitson: 1736 AD
Ann Lee (The Shakers): 1792 AD
Charles Wesley (Methodist): 1794 AD
Margaret McDonald: 1830 AD
Joseph Smith (Mormon): 1832 and 1891 AD
William Miller (Millerites): 1843 and 1844 AD
Ellen White (Seven Day Adventists): 1850, 1856 and "early 1900s" AD
Mother Shipton: 1881 AD
Watchtower Bible and Tract Society (Jehovah's Witnesses): 1914, 1915, 1918, 1920, 1925, 1941, 1975, 1994 and others more recent.
These "false prophet" predictions have continued to this day.
Why do we continue to believe these false prophets and their predictions? It is because they base their prediction on an erroneous interpretation of Jesus' statement here and elsewhere.
The reality is, this interpretation of "the son of man comes" is incorrect. The Greek word ἔρχομαι being translated to "comes" can also mean "to appear," but also "to arise" according to the lexicon. The Greek lexicon describes that when used metaphorically (which is how Jesus is using it) the word ἔρχομαι means "to come into being, arise, come forth, show itself, find place or influence"
Within Jesus' statements, he speaks variously of events to come as described by this Greek word ἔρχομαι. This includes the event following his coming persecution - the murder of his physical body. Following his persecution, Jesus arises from his dead body and appears again to his disciples, before ascending (again, "arising") to the spiritual realm and the Supreme Being.
But now Jesus is speaking of what will come for his followers in the decades to come. We know he is talking about an event that will occur within decades, because he says, "you will not finish going through the cities of Israel before the son of man comes." So this obviously is not describing an apocalypse to come thousands of years later. It is describing something that will occur in their generation.
Indeed, this statement would make no sense unless Jesus is speaking of something that will occur within a short time from the time he is saying it. When Jesus says, "you" he is speaking to those around him. Obviously, he is speaking of events that will occur during their lifetimes.
So what event will be occurring within decades that bears this appearance of Jesus? And how does this relate to his disciples completing going through all the towns of Israel? And how is it connected with the coming persecution of his disciples, which Jesus is saying that "he who stands firm to the end will be saved"? What does Jesus refer to when he says to his disciples "to the end"?
Jesus is speaking of their time of death. The phrase "the son of man comes" is better translated to "the servant of humanity appears." (The translation to "servant of humanity" is explained here.)
Jesus is speaking of his appearance at their time of death - as Jesus will be escorting each of them back to the spiritual realm.
Remember that Jesus says before this, "All men will hate you because of me." In other words, he is telling them that if they stand firm in their conviction to serve Jesus, even though they will be hated and persecuted because of it, he will come for them at the time of death, and "save" them by bringing them back to the spiritual realm.
Jesus' statement is connecting their coming persecution to his appearance to them when they die ("in the end") when he says, "When you are persecuted in one place, flee to another."
It is the very next sentence that Jesus discusses the "son of man comes [servant of humanity appears]." So it is obvious that they will not be able to "flee" "in the end." They will eventually be killed ("the end").
So the "son of man comes [servant of humanity appears]" is specifically connected with their persecution and death at the hands of those who "hate you because of me."
Instead of simply saying they will be killed, he says that he will "appear." Why?
Jesus did not teach that when the body dies, it is all over.
He also did not teach that we would wait around in some imaginary purgatory state for some speculative time thousands of years in the future when the end of the world would come.
He taught that the spirit-person (the self) within the body moves on after the physical body dies. This is also a scientific fact, because when we see a dead body, the life (the self) is gone from that body. The body becomes lifeless because the spirit-person self has left. And for those who have dedicated their lives to following Jesus' instructions, he will be coming for them after death.
This fact that we leave our body at the time of death has been scientifically confirmed in clinical death experiences. In many of these cases in fact, many have described the same event: Being met by Jesus after their time of death.
This means that Jesus appeared to them at the time of death.
Jesus also clarifies here what being “saved” is. Ecclesiastical institutions and their teachers often teach that being “saved” means professing our allegiance to Jesus in a proclamation that states something like “I surrender to Jesus.” This proclamation is often portrayed emotionally in a public place for everyone to see, qualifying that person to be accepted by their fellow church members. In other words, this act is often used simply to gain the respect of others.
Jesus describes clearly how a person is saved: "he who stands firm to the end will be saved." He is telling his disciples that despite being persecuted, ridiculed and threatened, the person who remains committed to following Jesus' teachings will be saved. This means having determination. It means follow-through.
Consider Jesus' view of the public proclamations of "I surrender to Jesus" currently encouraged by ecclesiastical Christian organizations:
“Not everyone who says to me, 'Lord, Lord,' will enter the kingdom of heaven, but only he who does the will of my Father who is in heaven. Many will come to me on that day, ‘Lord, Lord, did we not prophesy in your name, and in your name drive out demons and perform many miracles? Then I will tell them plainly, ‘I never knew you. Away from me, you evildoers!” (Matt. 7:21-23)So it isn't enough to make proclamations about Jesus. It isn't enough to do lofty deeds in the name of Jesus, even if they include healing people, driving out demons and other 'miracles.'
What matters to Jesus, and what ultimately "saves" a person is described clearly by Jesus:
It is doing God's will. It is pleasing God.
A person who does the will of another wants to please that person. This is love. Love means wanting to please someone else. Jesus wants his disciples - and all of us - to learn to love the Supreme Being and live to please the Supreme Being.
And if we "stand firm" in our efforts to please the Supreme Being, we will ultimately be saved, and Jesus will come for us (appear - ἔρχομαι) to bring us back home to God's kingdom.