Calvin comes out swinging here, arguing that indulgences didn’t just drift into error—they grew directly out of a flawed view of satisfaction and ended up turning salvation into a marketplace, where grace was treated as something bought, sold, and distributed by human authority rather than received freely in Christ. He dismantles the idea of a “treasury of merits,” insisting that to supplement Christ’s work with the supposed surplus of saints is not a minor mistake but a direct attack on the sufficiency of the cross, repeatedly grounding his argument in Scripture that points to Christ alone as the one who forgives, cleanses, and redeems. He then brings in voices like Leo and Augustine to show this is not a new objection but a deeply rooted Christian conviction: no martyr’s blood saves, no saint adds to redemption—only Christ does that. Calvin sha ...