Luke 13:1-5 reads as follows:
"1 There were present at that season some that told him of the Galilaeans, whose blood Pilate had mingled with their sacrifices. 2 And Jesus answering said to them, Suppose you that these Galilaeans were sinners above all the Galilaeans, because they suffered such things?3 I tell you, No: but, except you repent, you shall all likewise perish. 4 Or those eighteen, on whom the tower in Siloam fell, and slew them, think you that they were sinners above all men that dwelled in Jerusalem? 5 I tell you, No: but, except you repent, you shall all likewise perish."
This brings up a good question. If sin is the cause of calamity, then why did Jesus say that the afflicted people did not sin any more than the other Galileans? Is affliction arbitrary? Not at all. The point that Jesus was making was not that these people suffered innocently, but that some sinners were afflicted, while the others were fortunate that affliction hadn't found them yet. I believe God is a covenant keeping God. He conditionally promised Israel, as a nation, protection and blessing in Deuteronomy 28, Deuteronomy 7, Exodus 15:26, among many other places. There are also other general promises of protection to the "righteous" in various passages (#2Ch 16:9, Ps 34:7, 41:2, 91:4, 125:2, Zec 2:5, Lu 21:18). Israel, as a whole, had fallen from their part of the covenant of protection. The consequences of this violation ended up with the hedge removed, and therefore the captivity under Babylon. Jeremiah is littered with warnings of this coming calamity. However, He kept giving them a way out: "And go not after other gods to serve them, and to worship them, and provoke me not to anger with the works of your hands; and I will do you no hurt." (Jer 25:6). So they had an "out", because they had a loving Father Who wanted the best for them (Jer 29:11). As a whole, they didn't take the out. They suffered under Babylon, Persia, and finally Rome during the time of Christ. Therefore, the historical context of Luke 13 is at a time when Israel as a whole (including the galileans who died as well as the ones who didn't die), was outside of their national covenant with God; They as a people were living out the curse of Deuteronomy 28 under Roman oppression. So perhaps the disobedience of the whole impacts the individual -- which seems to be the case in Old Testament theocracy. Jesus told His inquirers that those people who perished weren't worse sinners then they were. Nevertheless, they were sinners and deserving of death, as all of Israel was. In fact, it is likely that the rest of them "got theirs" as well, in 70 A.D.. God had just given them a few more years to repent than the others who died already.
Could the afflicted Galilaeans have prevented their doom? I believe so. Though the national covenant was violated, they still could have impressed God with "great faith" for daily protection. I don't think the absence of "great faith" (such as the centurion or syro-Phoenician woman) is a sin. However, having "little faith" has to be a sin. I believe that faith and believing prayer moves the hand of God. Had the syro-phoenican woman not pressed Jesus the way she did, she would not have had her daughter healed. I don't think it would have been a sin either -- it would have been a simple foregoing of something God "would have" done (due to His pleasure in faith). Hezekiah's earnest prayer for 15 years of life is a similar matter. It would not have been sin had he not prayed fervently. I think people forego these things all the time -- me included. Some of it could be considered sin, but not all. We "know in part" and we are not perfect in our faith in God. So I'm sure we give the enemy territory at times; I'm sure we don't make the wisest decisions all the time; I'm sure we don't avoid situations that we should/could have; etc, etc.. Are all of these imperfections personal sins, or just the result of the state of sin?? That's the question. I think it's a combination of the two. Yet they both open us up for problems. But thank God, He hears our prayers! Jesus' teachings on prayer were simple -- "anything is possible to Him that believes", "you'll have whatsover you desire", "Don't doubt that you have what you say", etc..... Now we have these promises on prayer, and a direct advocate with the Father to enforce them. I believe these are promises to every individual, not like a theocracy. So due to the covenant context, I don't think it is a direct comparison to compare the people in Lk 13 to you or I today under the New Covenant, especially without any details of the people involved.