John Calvin Commentary Isaiah 58:4

"Behold, ye fast for strife and contention, and to smite with the fist of wickedness: ye fast not this day so as to make your voice to be heard on high." — Isaiah 58:4 (ASV)

Behold, for strife and contention you fast. This verse ought to be connected with the end of the preceding verse; for, having in the former clause introduced hypocrites as complaining of the violence and harshness of the prophets, he assigns, in the latter clause, the reason why the Lord loathes their fasts and their other performances. It is because they do not proceed from pure affection of heart. What the inclination of their heart is, he shows from its fruits; for he sends them back to the duties of the second table, from which it is easily seen what we are. Purity of heart is manifested by our living innocently and abstaining from all deceit and injustice. These are the marks of pure affection, in the absence of which the Lord rejects, and even abhors, all external worship. Wherever, on the other hand, cheating, plunder, and extortion prevail, it is very certain that there is no fear of God.

Thus he reproaches hypocrites for using their fasts to give greater encouragement to sin and for giving a looser rein to their lusts. We have experience of this every day. Not only do many people fast to atone for their cheating and robberies and to plunder more freely, but even so that, during the time of the fast, they may have greater leisure for examining their accounts, perusing documents, calculating usury, and contriving methods by which they may lay hold of the property of their debtors.

For that reason, they frequently assign this labor to Lent and the stated times of fasts. In like manner, other notable hypocrites hear many Masses every day so that they may more freely, with less interruption, and under the pretense of religion, contrive their cheating and treachery.

Fast not, as you do this day. Finally, he rejects their fasts, however highly they may value them, because in this manner the wrath of God is still more provoked. Immediately afterwards, he also rejects their prayers.

That you may make your voice to be heard on high. From this it is evident (as we have explained fully in our exposition of Isaiah 1:11) that God approves of no duties that are not accompanied by sincere uprightness of heart. Certainly, no sacrifice is more excellent than calling upon God; yet we see how all prayers are stained and polluted by impurity of heart.

Besides, since fasting is usually joined to prayer, the Prophet takes this for granted. Since it is an appendage to prayer, he therefore forbids such men to offer up solemn prayer accompanied by fasting, because they will gain nothing, except that the Lord will punish them more severely. And from this we infer (as has already been said) that the Lord pays no regard to external works if they are not preceded by a sincere fear of God.

The kind of fasting that was customary among the Jews is not blamed here in itself, as if it were a superstitious ceremony, but rather the abuse of fasting and false confidence. This ought to be carefully observed, for we would need to deal very differently with the Papists if we blamed their fasts.

Their fasts contain nothing but superstition, being tied to this or that day, or to fixed seasons, as if during the rest of the time they were at liberty to feast greedily. They think that the flesh is unclean, and yet allow every kind of indulgence to it; provided only that they do not feast greedily on a fast day, they think that they have discharged their duty admirably well.

Therefore, since there is nothing in them that can be approved, we may absolutely condemn them.

But the dispute on this occasion was different. The fasting that the Jews observed was laudable in itself because God had appointed it; but a false opinion respecting it was censurable. Among the Papists, on the other hand, we must condemn both the false opinion and the institution itself, because it is wicked.

The Papists have this in common with the Jews: they think that they serve God by it and that it is a meritorious work. Yet fasting is not the worship of God and is not in itself commanded by Him in the same manner as those works which He enjoins in the Law.

Instead, it is an external exercise, which is auxiliary to prayer, or is useful for subduing the flesh, or testifying to our humiliation when, as guilty persons, we implore that the wrath of God may be turned away in adversity. The reader will find the use and design of fasting more fully discussed in our Institutes (Book 4, chapter 12:15-21).