Question: What is the purpose of fasting, and why don’t modern Christians seem to fast as much anymore?
What is fasting?
To cut to the chase, fasting is a voluntary and deliberate abstaining of something that is good, namely food, for a temporary period of time for the primary purpose of intensifying our spiritual need and longing for God. Within evangelical circles, this practice is often seen as strange and irrelevant, and there are some fundamental reasons why many modern Christians are unfamiliar with fasting today.
Fasting goes against the grain of Western culture in more ways than one. When the cultural cry of our hedonistic society is to “pursue pleasure as the greatest good,” compounded with their other doctrinal statements of expressive individualism and freedom, we begin to see why the practice of fasting has lost its relevance in today’s postmodern world. Why on earth would you want to be restrained by rules and regulations when living happily means living freely? When is it ever reasonable to be willing to just deny yourself of the sensual pleasures that your body naturally craves? Most pleasure-seekers would be naturally repulsed at the very thought of depriving themselves of recreational pursuits that bring them happiness and joy. And when I’m referring to the hedonists here, I’m not just talking about nonbelievers. I’m talking about Christians as well.
Fasting in biblical times
In spite of the unfamiliarity of this practice within modern evangelical circles, fasting was not as uncommon as we might think. Jesus and his own disciples fasted as part of their regular routines (see Matt. 4:1-4; 6:16). People in ancient biblical times practiced fasting as a way to express their longing and hunger for God. It was generally done in conjunction with prayer, and there were different variations of fasting; some avoided both food and water completely and others did partial fasts, some fasted for several days and others for many weeks.
Though many believed the duration and extent of sacrifice for a fast directly correlated with its degree of piety, the main emphasis of the fast was to enable worshippers to give their utmost attention to God. Abstinence from food and drink is a tangible expression of the understanding that God is more important than mere worldly pleasures.
And aside from the overall purpose of this cultural practice, there were also other additional applications of fasting that can be observed from Scripture. When Jesus was in the wilderness, he fasted for 40 days to withstand temptation from the devil’s schemes (Matt. 4:1-3). Amidst a great multitude of enemies from Edom who came to invade Judah, King Jehoshaphat proclaimed a fast for all throughout the nation; seeking the Lord in prayer for wisdom and strength to overcome his enemies and to exercise judgment on them (2 Chron. 20:1-30). Ezra proclaimed a fast to express his humility and dependence on God, seeking provision from Him to keep him safe on his journey to Jerusalem (Ezra 8:21-31).
Are we encouraged to start fasting?
All things considered, Scripture does not explicitly command Christians to fast. Piper helpfully says that:
‘Fasting doesn’t have the same place in Christianity that it does, for example, in Islam. The fasting that Muslims do during the month of Ramadan in Islam is a requirement of every real Muslim. You can’t really claim to be a Muslim if you say, “I am just not going to do Ramadan.”’ 
You can still claim to be a Christian, even if you typically don’t practice abstinence from food, drink, and sex. Nevertheless, we are not under the letter but under the Spirit; the Spirit-filled Christian is infused with new affections and desires to live and serve for the Lord with gladness. Fasting, then, is an exceptional means of expressing to our great God that He is more desirable than any of the good gifts He has bestowed on us. And so I would implore brothers and sisters to consider abstaining, for a brief period of time, from the many gifts of enjoyment that God has given you. Surrendering all these things may seem menial and excessive, but Piper also mentions that “fasting is a great test to confirm for ourselves that God is real to us” . Fasting lets you put your money where your mouth is and exclaim from your heart that you need God more than anything else.
You can choose to abstain from particular foods and drinks, from binging Netflix and K-dramas, or from your long gaming sessions with the boys. The duration of your fast and what you choose to give up is left to your discretion. Whatever you choose your fast to be, devote yourselves wholly to prayer and mediation. You may find this experience daunting at first, but performing a spiritual detox will rejuvenate your soul as you express your longing for the Bridegroom to return and establish His lordship in the world.
Christian fasting is not a means to manipulate God into giving us what we desire. It is not a means of accrediting salvific merit in order to be right with Him. Christian fasting is a means of worship that keeps our hearts fixated on the Lord as our one and only greatest treasure.
 – Why Do Christians Fast?. (2020). Retrieved 1 September 2020, from https://www.desiringgod.org/interviews/why-do-christians-fast
 – Ibid