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Why Do Christians Fast? Three Reasons Explained by St. Thomas Aquinas

Mar 23, 2017 By Gretchen Filz

Fasting is an ancient spiritual discipline taught in the Bible, and modeled for us by Jesus himself during his forty-day sojourn into the wilderness in preparation for his earthly ministry.

Why is fasting so important in the life of a Christian?

Three Reasons Why We Fast According to St. Thomas Aquinas

Below are three reasons as described by St. Thomas Aquinas from his Summa Theologica. These points are great to keep in mind for Lent, the traditional time the Church sets aside for denying our bodily appetite as an act of self-mortification and penance (which is actually good for our bodies, as well as our souls!).

An act is virtuous through being directed by reason to some virtuous good. Now this is consistent with fasting, because fasting is practiced for a threefold purpose.

1. First, in order to bridle the lusts of the flesh, wherefore the Apostle says (2 Corinthians 6:5-6): "In fasting, in chastity," since fasting is the guardian of chastity. For, according to Jerome "Venus is cold when Ceres and Bacchus are not there," that is to say, lust is cooled by abstinence in meat and drink.

2. Secondly, we have recourse to fasting in order that the mind may arise more freely to the contemplation of heavenly things: hence it is related (Daniel 10) of Daniel that he received a revelation from God after fasting for three weeks.

3. Thirdly, in order to satisfy for sins: wherefore it is written (Joel 2:12): "Be converted to Me with all your heart, in fasting and in weeping and in mourning." The same is declared by Augustine in a sermon: "Fasting cleanses the soul, raises the mind, subjects one's flesh to the spirit, renders the heart contrite and humble, scatters the clouds of concupiscence, quenches the fire of lust, kindles the true light of chastity."

Have you ever gone on a fast and experienced these benefits? If so, please share your experience in the comments below!


Continue reading St. Thomas Aquinas: Master Theologian, Mystic, and Poet

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Gretchen Filz Gretchen Filz

Gretchen is a Lay Dominican with a passion for fostering an increase in Catholic faith and devotion through content writing and journalism. She works as a digital content writer, creator, and marketer for The Catholic Company. In addition to blogging at, she is also editor of the daily devotional email and author at She holds an M.A. in Christian Apologetics and converted to the Catholic Church in 2011. She is also active in R.C.I.A., pro-life work, and various faith-based web projects.

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