Think how difficult it would be to get to the end of your life and have to admit that you have been serving Satan. Perhaps literal crucifixion would be easier for many in this condition. But, we should fight that sin with every fiber of our being, knowing that God has something much better than sin prepared for us. You must repent . . . Most people are honest enough to be able to look back in sorrow at some consequences that they have had to suffer because of their own sin.
Consequences always produce a type of sorrow.
The person who robs the local store and gets caught is sorry that he ever conceived of the plan. But this is a sorrow for getting caught, not one motivated by a genuine desire to change. John goes on to tell them not to take pride in their heritage. They would not be able to practice business as usual if they were going to be ready for the Messiah. Repentance is a most painful process, and the longer we put it off, the more painful it becomes.