As often as they find a buyer

Calvin's Institutes (1559)
Book 4 of 4 - External Means by which God Invites Us into the Society of Christ and Holds Us Therein

Chapter 18 - Rome's Mass a sacrilege

12-18 - Sacrifice in Mass and in Scripture

12. Before Christ, Israel had signs emphasizing the sacrificial nature of Christ's work. Now, after Christ, the church has signs emphasizing the benefits from that sacrifice. We have a table, not an altar.

13. There are sacrifices of praise and thanksgiving, and there are sacrifices of propitiation, seeking to achieve God's favor. OT sacrifices prefigured Christ's sacrifice of propitiation.

14. The mass is not a sacrifice that merits any favor before God, even if they claim the cross as the source of that favor. Then they claim to apply the benefits of a mass to a particular person, and sell the Mass "as often as they find a buyer."

15. In Plato's Republic, he mocks men who sacrifice to the gods and then think they can sin with impunity. This is what Rome encourages with the Mass.

16. Sacrifices of praise and thanksgiving include "all the duties of love." See Mal 1:11; Rom 12:1; 1 Pet 2:5-6; Heb 13:16; Phil 4:18. Part of this "reasonable worship" is the spiritual manner of NT worship, in contrast with "carnal sacrifices" in the OT.

17. The OT saints already understood this kind of sacrifice - Ps 141:2; Hos 14:2; Ps 50:23; 51:19; Heb 13:15. In this way we are a priesthood, and the Supper involves a sacrifice of praise, through the only mediator, Jesus Christ.

18. Apart from all the further corruptions of it, the Mass in its purest form "swarms with every sort of impiety, blasphemy, idolatry, and sacrilege." Kings and nations are drunk with it; Satan uses it to get men to trust it instead of Christ for their salvation. The Mass is the Helen for which empires fight with rage; it involves "spiritual fornication."