Charles Spurgeon 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, ye fast for strife and debate, and to smite with the fist of wickedness:

Even in their fasts, they disputed with one another; one said the fast should be on such a day, another would keep it on another day; and no doubt there are some professing Christians who are very zealous, mainly out of spite against other professors; they with as much zeal keep fast days or feast days the wrong way as others do the right way. It is a pity when this sort of party spirit is mixed up with the observances of religion.

Ye shall not fast as ye do this day,

Some fasted in order to appear very religious. "Oh!" people would say, "such a man must be very good; he fasts three times in the week." That is a kind of fasting to which God has no respect. To feel pride while we fast with the stomach, is a poor way of showing how holy we are.

Behold, ye fast for strife and debate, and to smite with the fist of wickedness: ye shall not fast as ye do this day, to make your voice to be heard on high.

The best sort of mere external religion will soon turn sour. If you do not worship the Lord in a right spirit, God will loathe the very form of your service. Why, you might, by hypocrisy, make even prayer-meetings to be hateful in the sight of God; and the ordinances may be made as abominable to God as the mass itself. You can soon degrade sermon-hearing into mere listening to oratory, and the Sabbath-day may easily become an object only of superstitious and formal observance. The heart – the heart is everything; if that is wrong, it sours the sweetest things under heaven.

Behold, you fast for strife and debate, and to smite with the fist of wickedness: you shall not fast as you do this day, to make your voice to be heard on high.

They were fond of getting into religious disputes; and when they had a fast day, they fell to loggerheads about different doctrines, and they got angry with one another until they began to smite with the fist of wickedness, and they thought that a day spent in that manner would be acceptable to God. What kind of a God would he be?