“The Son of Man is going to be delivered into the hands of men...” (Matthew 17:22-23)

“The Son of Man is going to be delivered into the hands of men. They will kill him, and on the third day he will be raised to life.” (Matthew 17:22-23)

Why did Jesus tell them he would be 'delivered into the hands of men'?

When Jesus returned to Galilee, he described the sacrifice he would be making in the coming days.

Jesus didn't have to tell his disciples what was going to happen to him. Why did he then? Because Jesus wanted them to be prepared to lose him.

Following being told, his disciples were grief-stricken:
And the disciples were filled with grief. (Matt. 17:23)
Jesus wanted them to be sure that not only did he know the sacrifice he would face. The word "delivered" is translated from the Greek word παραδίδωμι (paradidōmi) which means, according to the lexicon, "to give into the hands of another" or "to give over into (one's) power or use."

And "men" is translated from the Greek word ἄνθρωπος (anthrōpos), which can mean "men" or "mankind" or "humanity."

Jesus is distinguishing between being given to mankind or men from being given to the Supreme Being. In the latter, one will be protected and sheltered. But in the former, Jesus knew he faced the wrath of men. Why? Because he understood that he threatened the power and authority of the high priests among the temple institution. This is because Jesus was God's representative.

What does he mean by 'kill him' and 'raised to life'?

He also wanted them to understand that the real Jesus - the spiritual person within - will rise after the death of the physical body.

Jesus describes the ascension as “life.” Why life? Actually, the original Greek does not mention "life." It simply ends with raised - or raised up - from the Greek word ἐγείρω (egeirō) which means "to arouse, cause to rise" according to the lexicon.

Thus we can understand from this that Jesus is not speaking of death here. The word "kill" is translated from ἀποκτείνω (apokteinō) which refers to mortal death - the death of the physical body.

So what will rise then - from the physical body? We know that Jesus is saying that the physical body will be killed, so what will rise must not be the physical body. This is confirmed later when Mary and others do not recognize Jesus when he rises. They do not recognize him because the physical body did not rise - the spiritual person within - Jesus himself - rose.

We can see elsewhere that Jesus made a distinction between the physical body and the spiritual person within - also referred to as the "soul":
"Do not be afraid of those who kill the body but cannot kill the soul." (Matthew 10:28)
We can see how Jesus is discriminating between the physical body and the spiritual person within. The spiritual person (spirit-person) is eternal while the biological body is temporary. The point Jesus is making is that we are not the physical body. 

The physical body typically has a lifespan of 50-100 years, after which the spirit-person leaves the body. Then the body decomposes.

Did Jesus really 'rise' in three days?

If we go by the timeline of the four Gospels, Jesus didn't reappear to his followers after three days. He appeared to them after two days.

If Jesus was crucified on Friday afternoon, and he reappeared to his followers on Sunday morning, that would be two days following the crucifixion. 

The 'third day' would be Monday.

This makes the timeline questionable unless we count the day of the crucifixion as day one. In other words, if Jesus is suggesting that on day three he will reappear, that would work with the timeline, as we assume day one is the beginning of the timeline.

Whether the timeline is accurate, the central proposition is that Jesus is suggesting that he will reappear to his followers two days after being crucified. How did he do that?

Jesus appeared much as an angel might appear in this world. Jesus' body died and his spirit-person was able to reappear through an apparition of sorts. Why?

Jesus was visiting his followers in a last-ditch effort to convince them to devote themselves to God so they could return home to the Supreme Being - and bring others with them. Consider this statement, made by Jesus, while in an angel-like body days after the death of his body:
"Go into all the world and preach the good news to all creation. Whoever believes and is baptized will be saved, but whoever does not believe will be condemned." (Mark 16:15)
How do we know that Jesus had left his body and appeared before his followers in an angel-like body? Consider this statement from Mark:
Afterward Jesus appeared in a different form to two of them while they were walking in the country. (Mark 16:12)
Thus we can know that Jesus left his physical body behind. Otherwise, they would have recognized him. He appeared once more before his followers, pleading with them to continue his teachings. He wanted them to take on the responsibility of teaching humanity about God. He wanted them to bring home others, as he had.

That is why Jesus referred to himself as the "Servant of Humanity" (a more appropriate translation of υἱὸς τοῦ ἀνθρώπου than "Son of Man").

Did Jesus die for our sins?

Many teach that Jesus died for our sins. Is that really true?

When Jesus returned to Galilee, he described the sacrifice he would be making in the coming days. The account of Jesus' trial from the four Gospels indicates that Jesus was persecuted because of his teachings. Both Pilate and the Chief Priest were questioning Jesus about his teachings: Did he say this or that.

During this questioning, Jesus would not retract his teachings. He stood by them.

This means that Jesus' sacrifice was about him making a stand regarding his teachings about the Supreme Being.

Just consider a person who was to teach something and the government or another dominant institution were to condemn the teaching and threaten the teacher with death if the teacher doesn't stop teaching those things?

Most teachers would stop teaching those things because they didn't want to die.

Not Jesus. Jesus wasn't afraid. He was willing to be killed in order to continue teaching. He was ready to die for his teachings.

This is also indicated when Jesus appeared before his disciples after his persecution. He did not tell them that they had been saved by his crucifixion. Neither did he tell them to teach such a philosophy to others.

Rather, Jesus asked his disciples to take on disciples as he had, and pass his teachings on to others.

If we accept that Jesus' teachings can save us from our sinful nature, then we can accept that Jesus died for our sins.

Truly, Jesus' teachings can save us. In particular, we can identify his 'greatest' teaching:
“ ‘Love the Lord your God with all your heart and with all your soul and with all your mind.' This is the first and greatest commandment. And the second is like it: ‘Love your neighbor as yourself.’ All the Law and the Prophets hang on these two commandments.” (Matt. 22:37-40)