Some people told Jesus about an incident in which Pontius Pilate had some Galileans killed by mingling their blood with the blood of their animal sacrifices (Lk 13:1-5). Although we do not know why Pilate did this and what issue there was with these people, it was obviously considered a gruesome thing. It was particularly disturbing to Jewish people who used animal sacrifices in their worship of God and in their seeking atonement for sin. This shows us that Pilate was not exactly pro-Jew, but the real question is why these people told Jesus about this incident. Jesus took this opportunity to explain something essential to us all - the universal need of repentance.
Jesus responded to these people by asking them a rhetorical question. Did they think the subjects of Pilate's actions were worse sinners than everyone else who lived in Galilee because this happened to them? The Lord said they were not. To God, sin is sin. The Bible does not categorize sin into ones that are not that serious and ones that are truly dangerous to our souls. All sin leads to spiritual death (Gen 2:17, Rom 6:23). The closest thing to categorizing is Jesus talking about blaspheme against the Holy Ghost (Lk 12:10), and John talking about a sin unto death (1Jn 5:16-17). This more relates to sins where people have crossed a spiritual line and done themselves such damage that they do not recover. It is not that God can't save them, but people can destroy their own conscience and desensitize it to sin (1Tim 4:1-2, Titus 1:15). Passages such as Hebrews 6:4-8 and 2Peter 2:20-22 are sometimes misunderstood. They do not mean that when someone errs, they are lost forever. This is talking about a clear decision to completely reject God and salvation with words and behavior that make it clear to God that He is no longer welcome in people's lives, so God honors their desire to be left of Him. This is after God has repeatedly attempted to offer repentance. If someone still has a conscience toward God, it is not too late to repent. Only God can decide these situations.
It was not a coincidence the people chose an incident involving Galileans. They were considered the low class, uneducated, uncultured, hillbillies. Galilee was actually the hill country of northern Israel. Calling someone a Galilean was an insult (Jn 7:52). Even the apostle Nathanael, whom Jesus said had no guile, thought ill of Nazareth in Galilee (Jn 1:45-47). He almost dismissed the report of the Messiah being located because he was told He was from Nazareth. Ironically, he was from the nearby town of Cana of Galilee (Jn 21:2). The other apostles were also from Galilee (Acts 1:11). Isaiah had prophesied the Messiah would hail from Galilee (Is 9:1, Mt 4:15). It is noteworthy that these verses call it "Galilee of the Gentiles". It was seen as a haven for heathen people as well as the "low class" Jews.
Yet it was a very important area. Galilee was the site of one of the six cities of refuge (Josh 20:7, Josh 21:32). It was the home of Joseph, Mary, and Jesus (Mt 2:22, Mt 3:13, Lk 1:26). It was where most of the ministry of Jesus took place. He did not spend a lot of time in Judaea or Jerusalem. He did travel around and over the Sea of Galille (also known as the Sea of Tiberias and the lake of Gennessaret) a lot. Galilee was the place Jesus appointed to meet the apostles after His resurrection (Mt 26:32, Mt 28:8 & 10 & 16). It was the place of His first miracle (Jn 4:46). The people who were talking to Jesus apparently thought they were better than those Galileans. Jesus told them they needed to repent or they would perish just like they did. We have all sinned and need to repent (Rom 3:23).
Jesus them brought up an incident wherein the tower of Siloam fell on 18 people. That was in Jerusalem (Jn 8-9). He asked if they thought these people were worse than the other inhabitants of that city. He repeated that unless they repented, they would likewise perish. He was not saying that towers would also fall on them. He was saying they would be judged sinners and lost forever.
When Jesus was dealing with the man born blind, He was asked whose sins caused his blindness (Jn 9:2-3). Jesus said it was not an issue of who sinned, but God was going to use it for His glory. Later, the religious hypocrites showed their pride and lack of repentance as well (Jn 9:13-34). Repentance has nothing to do with good things happening or bad things happening. Good things happen to bad people, and bad things happen to good people. Ask Job. Jesus said He makes the sun to rise on the evil and the good, and sends rain on the just and the unjust (Mt 5:45). Whether we are from the country or the city, whether we are rich or poor, whether we have had it good or tough, we all need repentance. It is the great equalizer. No one is great or small at the foot of the cross of Jesus Christ.
Repentance is not God beating us up, nor is it us beating ourselves up. It is not about judgment. It is about forgiveness. Although there is no special formula of words to be used, it can be characterized like this: "God, I am sorry for my sins. Please forgive me, and help me to change." Repentance is not a momentary event. It is a lifetime commitment to change. It is not being sorry about the earthly consequences of our sins, or being sorry we got caught. It is being sorry for what sin did to our relationship with God. When we initially repent, we do not become perfect and sinless. We become forgiven of the past. We will continue to make mistakes, although forgiveness is not a license to sin again (1Jn 1:5-2:4). We cannot continue in a lifestyle of sin and call ourselves saved. Jesus does not save us in our sins. He saves us from our sins. There must be change. Repentance is the agent of that change. Repentance is not an emotion, although emotion can be helpful in the moment. Repentance is a decision that must stay in force after the emotion dissipates. It requires an act of the will to maintain. A neglected altar will fall into ruin and will need to be repaired before it can be used again (1Ki 18:30, 2Chr 33:16). It is better to maintain it.