Dr. Faustus (moment that stuck out)

The one moment that stuck out to me after ending the book was the fact that it ended to abruptly.  When the 24 years was up and he was expecting the Devils to come take him away at midnight, I was completely confused because one minute he was making grapes for the Duke and Duchess and the next he is being convinced by an old man to repent for his life.  The last two scenes seemed to come rather fast so the readers weren't able to see all of the magic he had performed.  The question I was stuck with was how could he go 24 years without the fear of losing his soul to Lucifer, but when there is only a matter of hours left he then decides to repent?  Sins should be forgiven but you also must honestly feel as though you did wrong, not when it finally comes back to bite you.