Isaiah 58

The people of Israel had gone through the motions of serving the Lord and fully expected Him to do their bidding.  The Lord sees right through this,  calling it transgressions and sin.
They "seek" Him, "day by day". v2
They"delight to know [His] ways" 
They "ask [Him] for just decisions". 
They "delight in the nearness of God".
And they fast. v3
They "humble" themselves.
But, God does not answer them.

For God sees through the religious activities and into their hearts. 
They are fasting to "find their own desires" v3
They treat their workers harshly.
They "fast for contention and strife and to strike with a wicked fist." v4
They fast, not " to make your voice heard on high"... but to make themselves seen among men.
They may humble themselves, bow their heads, put on sackcloth and ashes... they may do all the "right" things... but their motivation is all wrong.

Jesus preached about this very thing in Matthew 6:
"Beware of practicing your righteousness before men to be noticed by them; otherwise you have no reward with Father who is in heaven.... And whenever you fast, do not put on a gloomy face as the hypocrites do, for they neglect their appearance in order to be seen fasting by men.  Truly I say to you, they have their reward in full." ( v 1, 16)

The Lord tells us what He desires.. what a true fast should be, " Is this not the fast which I choose, to loosen the bonds of wickedness, to undo the bands of the yoke, and to let the oppressed go free, and break every yoke?"

The Israelites were guilty of slavery.. of their own people.  They didn't obey the Law regarding the treatment of others.  They didn't help the widow or orphan.  They didn't care for the poor and needy. They would take their fellow Jew's fields, vineyards, houses, money, etc.  Nehemiah addressed this problem which still existed after the return from exile.. " Again I said,'The thing which you are doing is not good; should you not walk in fear of our God because of the reproach of the nations, our enemies?.... Please, let us leave off this usury. " ( Nehemiah 5: 10-12)

The Lord calls for His people to treat others justly and with mercy...His chosen fast is to
".. divide your bread with the hungry and bring the homeless poor into the house; when you see the naked cover him; and not to hide yourself from you own flesh." v7

When our hearts are His.. we have what James calls, " true religion"  :
" This is pure and undefiled religion in the sight of our God and Father, to visit the orphans and widow in their distress, and to keep oneself unstained by the world." 

And the rewards are great!
"Then your light will break out like the dawn, and your recovery will speedily spring forth; and your righteousness will go before you; the glory of the Lord will be your rear guard.  Then you will call, and the Lord will answer; You will cry and He will say, 'Here I am'" ( v8)
Light
Satisfaction
Strength
Fruitfulness
Restoration

To live in reverence and obedience, for the Jews, would begin with the keeping of the Sabbath.
Turning from doing their own pleasure. Not speaking their own word or seeking selfish desires.
Considering the sabbath a delight,  setting the day apart for the Lord. Honoring and delighting in the Lord... In other words, putting God first! Especially on His holy day!!!
This is God's desire.  Not going through the motions while living in sinful disobedience.

How does this apply to us? We have the same problem that Israel did.  We have many who call themselves Christians, who go through the motions of church.  We attend services, give our tithes, celebrate communion, sing the songs, and even pray or speak the right words. ...
but our hearts are not yielded entirely to the Lord . We don't care about our neighbors, families, and friends enough to do anything when they are struggling or in need.   We hold onto our money instead of giving to those in need. Or we lord it over those who have come to us for help.

Father in heaven,  hallowed be Your name.  Your will be done.  Your kingdom come...  in us and through us... I do not want to fall into the habit of "religion".. but to live according to the power of Your Spirit in me .. walking in mercy and compassion, loving others, and living in surrender to You.
Transform me, renewing my mind, by Your Word and Spirit, I pray... in the Name of Jesus, my Lord and Master. Amen.