I want to test the ability of students to read a passage and answer questions about it. Could you please come up with a good question for the passage "He insisted that, since forgiveness was God's alone to grant, those who claimed that indulgences absolved buyers from all punishments and granted them salvation were in error. Christians, he said, must not slacken in following Christ on account of such false assurances."? 

The idea that indulgences did what they were marketed as is a?