It’s an important point. There are some very strange ideas and practices and doctrines that come out of the RCC that are not found in the bible. This whole indulgences thing is just one of many.
I agree that it is important, but I disagree that there are "some very strange ideas and practices and doctrines that come out of the RCC".
The concept of indulgences are very ancient and are found in Scriptures. To begin with, have you considered Matthew 16:19 or Matthew 18:18? Or we could go back further and look at the Jewish OT - which clearly mentions the idea of penance and acts of contrition for one's sins (such as wearing sack clothes and dousing one's head with ashes). The Church has been given authority to bind and loosen, to punish those within, or to free one from the effects of temporal punishments.
Regards
The idea of making restitution for wrongs done isn't Biblical?
Interesting ...