Calvin on being present for the Mass (from The Unlawful Rites of the Ungodly) and the sin of occasional hearing:
Come now and consider with me, in regard to a pretended observance of the Mass, with what kind of conscience you can be present at the performance of its mysteries. Immediately on your entrance, the altar offers itself to your view, differing little from a common table, but proclaiming, by its very name, that it is to be used for sacrificing ! This itself assuredly is not free from blasphemy. You see the Priest coming forward, who boasts that, by the anointing of four fingers, he has been appointed mediator between God and man, who, carrying off from the faithful of the Church, and from -the Supper itself, that promise in which Christ gives his Body and Blood to his servants, to be eaten under the symbols of Bread and Wine, arrogates it to himself and his fellow slayers, who dishonour his heavenly Supper by giving it the name of Mass, in which it is completely inverted and deformed. The people stand by, persuaded that every one of these things is Divine ; you stand among them pretending to be similarly affected. When the impostor has gone up to the altar, he begins the play with acts partly motionary, partly stationary, and with those magical mutterings by which he thinks himself, or, at least, would have others to think—he is to call Christ down from heaven, by which he devotes Him when called down to Sacrifice, and by which he procures the reconciliation of God with the human race, as if he had been substituted in the place of a dead Christ ! These acts you see received by the whole multitude, with the same veneration as those above-mentioned ; you shape your features to imitate them, when they ought visibly to have expressed the utmost abhorrence !
Will it still be denied to me that he who listens to the Mass with a semblance of Religion, every time these acts are perpetrated, professes before men to be a partner in sacrilege, whatever his mind may inwardly declare to God ? At last, behold the Idol (puny, indeed, in bodily appearance, and white in colour, but by far the foulest and most pestiferous of all Idols !) lifted up to affect the minds of the beholders with Superstition. While all prostrate themselves in stupid amazement, you, turning toward the Idol with an expression of veneration, prostrate yourself also. What effrontery must ours be, if we deny that any one of the things delivered in Scripture against Idolatry is applicable to the Idolatry here detected and proved ! What ! is this Idol in any respect different from that which the Second Commandment of the Law forbids us to worship ? But if it is not, why should the worship of it be regarded as less a sin than the worship of the Statue at Babylon ? And yet the three Israelites, to whom we above referred, shuddered more at the idea of offering- such worship than of suffering death in its most excruciating form. If the Lord declares the impurity of the vulgar superstitions of the Gentiles to be such that they are not to be touched, how can it be lawful to keep rolling about in such a sink of pollution and sacrilege as here manifestly exists ? Taking the single expression which gives the essence of all the invectives which the Apostle had uttered against Idolatry—that we could not at once be partakers at the table of Christ and the table of demons—who can deny its applicability to the Mass? Its altar is erected by overthrowing the Table of Christ, and its feast is prepared by plundering, lacerating, defiling the meats prepared for the Table of Christ. In the Mass Christ is traduced, his death is mocked, an execrable idol is substituted for God—shall we hesitate, then, to call it the table of demons? Or shall we not rather, in order justly to designate its monstrous impiety, try, if possible, to devise some new term still more expressive of detestation? Indeed, I exceedingly wonder how men, not utterly blind, can hesitate for a
moment to apply the name ” Table of Demons” to the Mass, seeing they plainly behold in the erection and the arrangement of it the tricks, engines, and troops of devils all combined.
Source: https://puritanboard.com/threads/christians-visiting-churches-which-preach-a-false-gospel.95345/, Comment 3