On the reason for tragedy

This (Monday) morning's sermon was on St Luke 13:1-5:

There were present at that season some that told him of the Galilaeans, whose blood Pilate had mingled with their sacrifices.And Jesus answering said unto them, Suppose ye that these Galilaeans were sinners above all the Galilaeans, because they suffered such things? I tell you, Nay: but, except ye repent, ye shall all likewise perish. Or those eighteen, upon whom the tower in Siloam fell, and slew them, think ye that they were sinners above all men that dwelt in Jerusalem? I tell you, Nay: but, except ye repent, ye shall all likewise perish.

And the sermon: