Why do Catholics fast during Lent?

“Love the Lord with all your heart, and with all your soul,

and with all your MIND”--Matt 22:37

Question:  Why do Catholics fast during Lent?  Doesn't the New Testament abolish fasting?  Doesn't the Bible tell us that God does not want us to fast, but rather to set captives free?

While it is true that Scripture does state that the fasting God wishes is for us to "set captives free"--it must be understood that it's not fasting itself that God condemns, but rather external works done without internal sincerity.

This, rather, is the fasting that I wish: releasing those bound unjustly, untying the thongs of the yoke; Setting free the oppressed, breaking every yoke;--Isaiah 58:6

It is, however, NOT TRUE that the NT abolishes fasting.  In fact, the NT speaks often of fasting.

    Whoever wishes to be my follower must deny his very self, take up his cross each day, and follow in my    steps.--Luke 9:23
 
    Then, completing their fasting and prayer, they laid hands on them and sent them off.--Acts     13:3
   
    But the days will come, and when the bridegroom is taken away from them, then they will         fast in those days.--Luke 5:35

    But when you fast, anoint your head and wash your face--Matt 6:17

(note the "when you fast", not "if you fast"). 

Protestants seem to consider the Catholic practice of fasting during Lent at best a curiosity, and at worst a testament that Catholics really do believe that we can "work" our way into heaven.  In fact, on this anti-catholic website by an ex-Catholic, he states, "But we are never taught in Sacred Scripture that fasting and other personal sacrifices atone for sin."

Just to be clear:  the Catholic Church does NOT teach that our fasting will "atone for sin".  Only Christ atones for our sins.  (This is a sad testament that those who leave the Catholic Church, as the author of the above quote did, usually don't even know the teachings of the Church that they left.)

From Catholic convert Jimmy Akin:  "When I was a young Protestant and much opposed to any form of penance ("Hey, Jesus forgave our sins! Why do we need to do penance?"), my Episcopalian aunt pointed my attention to the Sermon on the Mount, where Jesus says: "And when you fast, do not look dismal, like the hypocrites, for they disfigure their faces that their fasting may be seen by men. Truly, I say to you, they have received their reward. But when you fast, anoint your head and wash your face, that your fasting may not be seen by men but by your Father who is in secret; and your Father who sees in secret will reward you" (Matt. 6:16–18; cf. Mark 2:18–20)."

So why do we fast?  Why do we practice self-denial and sacrifice? 

Because we love.

As anyone who's ever loved, (parent, spouse, child, sibling), we know that it's absolutely impossible to love someone without sacrifice and self-denial.  We get up at 3am to tend to a coughing child. That's sacrifice.  We sit vigil at our sibling's bedside at the hospital. That's self-denial. We drive an hour away to watch our spouse finish a marathon.  Sacrifice. 

There is no love without sacrifice. 
While our fasting does not atone for others' sins, it can produce good in others. It echoes what was mentioned in another apologetics discussion regarding the "dignity of causality".  God gives us the dignity of actually causing good, by our offering up a prayer/work/sacrifice for the sake of another's intention.  It is a supreme privilege we've been given as Christians to be able to change the course of someone's destiny by our actions/prayers/sacrifices.  Just like our physical efforts produce food on our table for our families--God does not simply magically make the food appear on our plates--our spiritual efforts also produce fruit in the world.

Our self-denial/sacrifices/penance during Lent also produces good in us.  For who can doubt that in our privileged, indulged, affluent society--where entertainment is nano-seconds away at our fingertips at every minute of the day--that a spiritual retreat from these things is good for our souls?  Our human natures do not thrive when over-indulged!  How wise of the Church to "mandate", so to speak, a spiritual "time-out" from our tendency to pamper ourselves.  It's just not healthy physically. And it's not healthy spiritually.  Who wonderful for us that Holy Mother Church is always looking after her children's health!

Catholic Bible online

Catechism of the Catholic Church online

A Short Primer on Fasting

Why Do Christians Eat Fish on Friday?

"Always be prepared to give an answer to everyone who asks you to give the reason for the hope that you have. But do this with gentleness and respect" - 1 Peter 3:15