Throughout the bible we see constant examples of God's servants taking time to fast and pray. In the old testament we see examples from Esther who directed the Jews to fast for her protection before she went before the king, Samuel who declared a fast of repentance for all of Israel, Elijah who was directed by God through the wilderness when he was in a state of hopelessness, Ezra who fasted for protection and direction when facing danger on the trip back to Jerusalem, and Daniel who was fasting as a state of mourning and in the end received a major prophetic vision. In the new testament we see the practice of fasting was still prevalent through the example of John the Baptist, Jesus and the disciples. We also see Jesus constantly talking about the proper ways and motivations to fast.
If fasting was so prevalent throughout the Word of God it seems clear that it should be something prevalent in our lives if we truly want to see the power of God. In Isaiah 58 we see a great description of what fasting, with the right motives, can bring us. Isaiah begins the chapter by rebuking the people for their sin and for fasting with the wrong motives. We see in verse 3 that they had been fasting and had been asking God why He was not responding to their fasting but God calls out their motives. He shows hem that there fasting has no value if they have no desire to live as He called them to live.
But then in verse 6 God lays out the "the fast that [He has] chosen". This is what fasting with the right motives is for: "to loose the bonds of wickedness, to undo the heavy burdens, to let the oppressed go free, and that you break every yoke". In verse 7 He adds on that fasting is to help feed the hungry and support the poor. That is some power that has been forgotten today!
To loose the bonds of wickedness:
Fasting has the power to set people free from sin and addiction. Do you have a sin that you just can't seem to stop? You know that it's wrong, you don't want to do it, but somehow you just feel bound or trapped? Maybe it's a commonly known addiction like drugs or alcohol, or maybe it's an addiction to money, greed, power, lust? Fasting has the power to set you free from that thing!
To undo the heavy burdens:
Jesus said "my yoke is easy and my burden is light." (Matt 11:30) But even though His yoke is easy we have a tendency to allow heavy burdens to way us down. Maybe we are under the burden of guilt or shame, maybe we have taken on responsibility for a family member who is making wrong decisions despite knowing that we should give them up to God. Whatever it may be, God said that fasting can allow us to let go of those heavy burdens. Fasting can loose them from our lives and help us to find the light burden that Jesus promised us.
To let the oppressed go free:
Do you know some one who is constantly tormented by fear or worry? Or maybe they are under the oppression of bitterness or sickness? Fasting has the power to set them free from that oppression! Fasting for family and friends is powerful and can completely change their life!
To break every yoke:
God then brings it together to make it clear that the fasting He chooses will break anything that binds us, that holds us back. Whether it's sin, addiction, burdens, or demonic oppression it can be broken through prayer and fasting!
To feed the hungry and support the poor:
In verse 7 God tells us that there are practical applications to fasting as well. When we give up our food to seek Him then we can use that extra food to supply for the needs of others. This can still be practiced today. Maybe you go out for lunch when you're at work. Every day you fast you can set aside the money that you would have spent and give it to feed the hungry. Maybe you decide to fast Starbucks for a month and collect the money you would have spent to buy clothes for the homeless or the single mother down the street. Our fasting has amazing power in the spiritual realm but it also has practical applications to meet the needs of your community.
God then sums it all up in verse 8. When we are fasting for the right reasons this is ultimately what we can expect:
"Then your light shall break forth like the morning,
Your healing shall spring forth speedily,
And your righteousness shall go before you;
The glory of the Lord shall be your rear guard."