In 1544 Calvin wrote a work entitled, The Necessity of Reforming the Church, and addressed it to, Charles V, who then had the title of, Holy Roman Emperor. The occasion was an Imperial Diet at Spires (Speyer), of which Charles was overseeing. His outline includes:
First, I must briefly enumerate the evils which compelled us to seek for remedies.
Secondly, I must show that the particular remedies which our reformers employed were apt and salutary.
Thirdly, I must make it plain that we were not at liberty any longer to delay putting forth our hand, inasmuch as the matter demanded instant amendment.
In order to enumerate the evils in the Church, he sets out to explain the essence of the Christian Religion:
If it be inquired, then, by what things chiefly the Christian religion has a standing existence amongst us, and maintains its truth, it will be found that the following two not only occupy the principal place, but comprehend under them all the other parts, and consequently the whole substance of Christianity, viz., a knowledge, first, of the mode in which God is duly worshipped; and, secondly, of the source from which salvation is to be obtained. When these are kept out of view, though we may glory in the name of Christians, our profession is empty and vain. After these come the Sacraments and the Government of the Church, which, as they were instituted for the preservation of these branches of doctrine, ought not to be employed for any other purpose; and, indeed, the only means of ascertaining whether they are administered purely and in due form, or otherwise, is to bring them to this test.
If any one is desirous of a clearer and more familiar illustration, I would say, that rule in the Church, the pastoral office, and all other matters of order, resemble the body, whereas the doctrine which regulates the due worship of God, and points out the ground on which the consciences of men must rest their hope of salvation, is the soul which animates the body, renders it lively and active, and, in short, makes it not to be a dead and useless carcass.
He then builds upon the ideas of Doctrine, Worship, and Government. Regarding worship, he gives the typical Reformed definition and principle of Regulated Worship.
Moreover, the rule which distinguishes between pure and vitiated worship is of universal application, in order that we may not adopt any device which seems fit to ourselves, but look to the injunctions of him who alone is entitled to prescribe. Therefore, if we would have him to approve our worship, this rule, which he everywhere enforces with the utmost strictness, must be carefully observed. For there is a twofold reason why the Lord, in condemning and prohibiting all fictitious worship, requires us to give obedience only to his own voice. First, it tends greatly to establish his authority that we do not follow our own pleasure, but depend entirely on his sovereignty; and, secondly, such is our folly, that when we are left at liberty, all we are able to do is to go astray. And then when once we have turned aside from the right path, there is no end to our wanderings, until we get buried under a multitude of superstitions. Justly, therefore, does the Lord, in order to assert his full right of dominion, strictly enjoin what he wishes us to do, and at once reject all human devices which are at variance with his command. Justly, too, does he, in express terms, define our limits, that we may not, by fabricating perverse modes of worship, provoke his anger against us.
I appreciated Calvin’s comments on the fruitlessness of zeal when not mixed with obedience to His precepts. The contemporary Church could take great instruction from this.
I know how difficult it is to persuade the world that God disapproves of all modes of worship not expressly sanctioned by his word. The opposite persuasion which cleaves to them, being seated, as it were, in their very bones and marrow, is, that whatever they do has in itself a sufficient sanction, provided it exhibits some kind of zeal for the honor of God. But since God not only regards as fruitless, but also plainly abominates, whatever we undertake from zeal to his worship, if at variance with his command, what do we gain by a contrary course? The words of God are clear and distinct, “Obedience is better than sacrifice.” “In vain do they worship me, teaching for doctrines the commandments of men,” (1 Sam. 15:22; Matt. 15:9). Every addition to his word, especially in this matter, is a lie. Mere “will worship” (ἐθελοθρησκία = e-the-lo-thrā-skē’-ä) is vanity. This is the decision, and when once the judge has decided, it is no longer time to debate.