Weren't They a Kind of 'Get out of Sin Free' Card?

I may not have this quite right, but it is my understanding that the practice on the part of the Catholic Church of granting indulgences -- sometimes freely given but sometimes purchased, the latter really pissing Martin Luther off -- was based on the notion not that the indulgence absolved you of guilt but that the indulgence removed the necessity of your being punished for something you, indeed, had done. And that, in fact, you were not entitled to an indulgence unless you felt guilty for your sin, which guilt is always the greatest punishment, is it not?

So this modern habit of going into drug and alcohol rehab after doing something bad is not the same as an indulgence in that those going into rehab use rehab not as a substitution for punishment -- at least, that's not the principle aim -- but as part of the larger argument that they were not responsible for their sin, in whole or in part. It is not just that they want to be absolved of punishment. They want to be absolved of responsibility.

Do I have this right?

Sophocles would have been filled with such contempt. Just think of it: Oedipus Rehab.