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The One Thing Is Three: How the Most Holy Trinity Explains Everything

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With humor and ease, Father Michael Gaitley, MIC, deftly unlocks the “one thing,” the key to the Church’s wisdom, and the greatest mystery of the Catholic faith: the Most Holy Trinity. Far from being a scholarly or academic read, The “One Thing” is Three makes deep theology accessible to every-day Catholics. What’s more, it makes even what’s familiar or forgotten appear in a way that’s new, exciting, and relevant. Thus, The “One Thing” is Three brings its readers a unique and powerful experience of the faith. It’s the perfect book for the Year of Faith.

380 pages, Paperback

First published November 1, 2012

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About the author

Michael E. Gaitley

18 books231 followers
Father Michael Gaitley, MIC, is a member of the Congregation of Marian Fathers of the Immaculate Conception. Prior to his ordination to the priesthood, he received a Masters Degree in Theology and a Licentiate Degree in Moral Theology.

After his ordination to the priesthood, Fr. Michael succeeded Fr. Seraphim Michalenko, MIC, as the director of the Association of Marian Helpers, a spiritual benefit society with more than 1,000,000 members. As director, he has launched a new pastoral initiative called Hearts Afire: Parish-based Programs for the New Evangelization (HAPP).

He frequently appears on EWTN and preaches retreats throughout the country on topics such as Divine Mercy, Consoling spirituality, and Marian Consecration.

When he is not preaching missions and retreats, Fr. Michael lives and works on Eden Hill in Stockbridge, Mass., home of the National Shrine of The Divine Mercy.

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Displaying 1 - 30 of 30 reviews
Profile Image for booklady.
2,678 reviews100 followers
June 6, 2014
As soon as I finished this book, I was ready to begin it again—mostly because I know I didn’t begin to absorb all the ideas contained therein. Even so, my copy is dog-eared. I have carried it everywhere these past few weeks: to Mass almost every day; to Adoration; it even went to Houston with me last week-end when I moved my daughter there.

However before I reread it, I will be taking Fr. Gaitley's recommendations about the writings of Sts. John Paul II and John Henry Newman. Maybe in that way, I can build up to Thomas Aquinas. My favorite books/authors are those who point me to others! It reminds me of literary ‘calling cards’: ‘Here’s your introduction to...’

The 'One Thing' Is Three is the third book in the series by Fr. Gaitley which forms a complete adult formation series. The first two, 33 Days to Morning Glory, and Consoling the Heart of Jesus, were mini-retreats, whereas this book is a little lesson in theology. The good thing is that it was easy to understand. Fr. Gaitley made it fun and broke down the difficult concepts for ordinary folks like me.

Fr. Gaitley calls himself a ‘professional seminarian’ because he spent 15 years in seminary, but it seems to be time well-spent as he went after wisdom and understanding the way some people pursue wealth and success.

The title The 'One Thing' Is Three refers to the Scripture passage in the Gospel of Luke (10:42) when Our LORD counsels a frazzled Martha who would have her sister help her with kitchen chores, “...there is need of only one thing. Mary has chosen the better part and it will not be taken from her.” The “One Thing” of course is God and He IS the Great ‘I AM’, the three Persons of the Blessed Trinity.

The Holy Trinity, one of the most controversial and least understood concepts of Christianity, if dropped—according to theologian, Karl Rahner, wouldn’t be missed! Father Gaitley doesn’t agree. In The 'One Thing' Is Three he shows how relationship among the three is central to our faith. Actually Fr. Gaitley began to build this premise in his first book and brings it to culmination here. As I was reading, the thought came to me, ‘I wish I’d had this book when some questions came up about the Holy Spirit during our group discussions for 33 Days to Morning Glory.’

The book is organized according to the three points of Communion: Communion with the Trinity—our final end; Transforming Communion—our immediate end; and Mission of Communion—our mission.

Tidbits gleaned for which I’m grateful:

1. Wisdom is realizing that hearing something over and over again is not repetition; it’s an invitation to go deeper. (Ha! I wish I could sell my kids on that!)

2. Vatican II was called to respond to a problem, but it wasn’t a heresy. Rather it was duplicity. In its own words, it calls out the great problem of Christians in the modern world: ‘...the split between the faith which many profess and the practice of their daily lives.’ Cardinal Karol Wojtyla (St. John Paul II) actually implemented Vatican II in his archdiocese as it was supposed to have been implemented everywhere, along a two-step program described in his book, Sources of Renewal: The Implementation of the Second Vatican Council, and by developing the theme described by the Council, known as communio, or a local Synod, a mini-Vatican II within his archdiocese.

3. “Notional” knowledge (as described by John Henry Newman) has to do with ‘large principles, ‘general laws,’ ‘common nouns,’ and most things abstract. Newman deplored things notional, indefinite and intangible in religion because of their inability to move the human heart. On the opposite end of the scale Newman would put the Blessed Sacrament: a real, concrete, bodily presence, an objective “fact.”

4. The sacraments DO something!”

5. There’s a primacy to Faith. Faith has to do with the mind and Hope and Charity have to do with the heart. The heart can see, but not very well. It can only see and respond to the things the mind (and all the senses) bring right before it.

6. There was a ghastly dialogue between the Personified Culture of Death (C of D) and a Reporter which culminated in this admission by the C of D: “Yes, I’m deeply gratified by more than a billion abortions in the last 30 years, and I look forward to ramping up the killing of the sick and elderly. But you have to understand that physical murder is not my greatest achievement. Spiritual murder is what I am truly aiming at. That’s the death I’m really all about. … I lure them with pleasure, riches, and praise till they’re puffed up little “I’s” with hearts as cold and hard as ice. And when their hearts die, their souls die, and then they’re mine.”

7. The contemplative outlook occurs when we see the deeper meaning in all of life; grasp its utter gratuitousness, its beauty, and its invitation to freedom and responsibility. It is the outlook of those who accept all of life as gift, discovering in all things the reflection of the Creator and seeing in every person His living image.

This book is the best book I have read so far this year and may end up being the most important book I read as well. I’ve watched the accompanying DVD series and, God willing, I am going to participate in a group study at a nearby parish this fall.

*“We must be willing to admit that, should the doctrine of the Trinity have to be dropped as false, the major part of religious literature could well remain virtually unchanged.” Karl Rahner, The Trinity, p.10
Profile Image for Loretta.
368 reviews235 followers
December 2, 2019
My priest at my church had a class on this book which started in July and just now ended. Conflicts of his schedule, vacations and space for the class prolonged it. At one point Father asked me to fill in for him one night! We joked with Father that the reading of this book took longer than the seven days it took God to create the world!! Thank goodness he has a good sense of humor and laughed at our statement!

The book did provide me with a deeper understanding of the Trinity. Father Gaitley does write in layman's terms for people who just don't understand theology, which is good. Parts of the book are very redundant but I'm sure that was because he wanted to drive his point home.

The videos we watched, that coincide with the book, were very good as well. Father Gaitley speaks well and captures his audience. The audience in his video and the ones who attended the class at my parish all seemed engaged.

Unfortunately, the next book in the series, You Did It to Me: A Practical Guide to Mercy in Action, was suppose to be read with the class after The One Thing Is Three: How the Most Holy Trinity Explains Everything, but now with the holidays and other commitments on Father's part and the participants in our class, he asked if we would read it at leisure and if we had any questions, he'd be happy to answer them. I haven't started it yet but I do plan on it. It's a small book, 216 pages.

There's great information at the end of the book on Divine Mercy/St. Faustina and there's a great Appendix called "The Great Oyster" that Father Gaitley provides titles of books for additional reading.

I think anyone wanting to learn more on The Holy Trinity should read this book and if your church offers a class with the videos I would highly recommend attending. I'm sure you wouldn't be disappointed.

Profile Image for Pat Gohn.
8 reviews4 followers
February 9, 2013
The Holy Trinity is the central mystery of the Catholic Faith, the heart of the Creed. That is reason enough to read The 'One Thing' is Three, to sure up one's theological knowledge. Fr. Michael Gaitley's style is very linear, yet conversational, making this a popular book for a general Catholic readership, as opposed to an academic reference work. Yet, great end notes offer clarity and further study if you want it. This book could also be a good book for a Catholic book club, or an addition to a catechism study series, or even a high school religion curriculum.
Profile Image for Regina Doman.
Author 30 books506 followers
February 15, 2014
This was an amazing book. I received it from the author at a trade show, and since I was a huge fan of his other book (33 Days to Morning Glory) I was excited to read this one. The book was a bit slow for me (but I often have to read theological books slowly) and for a long time I couldn't figure out what the entire point of the book was. But by the time I reached Part 3, it began to come together for me and by the time I reached the end, I knew I would have to read the book all over again to truly absorb it.

I think this book has already changed my life, because I am still pondering many of its points. I do recommend it, although it's not as accessible as 33 Days to Morning Glory. I will be reading it again, and soon.
Profile Image for Jacob Benne.
32 reviews1 follower
December 11, 2023
A great insight and intro into theology specifically not just logical and knowledge based theology, but making theology real and living it out.
9 reviews
May 18, 2014
A sign of intelligence is the ability to take a complicated topic and communicate it in a manner that is understood by experts as well as beginners. Fr. Michael meets this criterion in "The One Thing is Three."

Fr. Michael puts to very good use his background as a "professional seminarian" and writes an easy to read book that packs 2000+ years of Catholic Theology into approx 300 pages. If you are looking for an introductory crash course into the Catholic faith this book is for you.

One tip on reading "The One Thing is Three," make sure you have the time to read entire sections of the book in one sitting. Because he is cramming in two millennia of theology into one book there are few natural breaks. By trying to break it up into a few pages here and a few there you will not give yourself the time to contemplate what is being said and you will get the full value of the book.
209 reviews3 followers
May 22, 2017
I read this to learn about the co-equality of the Trinity, but did not find any reference to this at all. The book is much broader than I was expecting. It even goes into explaining why using artificial contraceptives are wrong. I guess the Holy Trinity really does explain everything.

As everyone says, this is a very accessible book. The most insightful takeaways for me were learning the most sacred passage in Holy Scriptures, the grace of the Sacraments, and the weight of the Eucharist.

Yet, I truly believe the author was off on some points. For example, he says that angels cannot smell flowers or hear birds sing because they are pure spirits. I would wonder then at the interaction of angels with the physical world as recorded in Scriptures. Moreover, the necessary (and absurd) conclusion to this would be that our God Himself cannot hear His own birds sing because He also is a pure spirit.

We also have different ideas on baptism, St. Mary, the image of God, the vision of Divine Mercy, Loyola's spiritual exercises, animals, and what ordering creation for the good of humanity looks like, but I digress. There are many pearls to be found here, like the interview with the Culture of Death and the section on spiritual motherhood. I'll keep this book for such pearls.
Profile Image for Barbara.
348 reviews5 followers
January 30, 2021
This book is not about the Holy Trinity. The Trinity is mentioned but is certainly not the topic of the book.

While Gaitley is a very readable author, he is beyond tangential. He veers so far off topic you feel compelled to just stop reading altogether.

Gaitley is so enamored with John Paul he defies credulity. He talks about John Paul and his wisdom on love, justice, mercy, and communio. Nothing could be further than the truth. John Paul is renowned for being the singular WORST pedophile enabler in Church history. He alone judged, excused, and protected hundreds of priests and bishops who committed sexual abuse. Even through and beyond his death, the Church worked to keep this vile secret. The Church then canonized him. And Gaitley, in this book, adulates him. Shame on all of them.

It appears the purpose of the book was not to teach about the Holy Trinity but to promote Gaitley’s order and line of books. We can do better than this in the Catholic Church. And we should!!

Perhaps Father Gaitley should try again to truly write about the Holy Trinity.
Profile Image for Michael Vidrine.
188 reviews16 followers
October 6, 2022
This book is good for what it is (i.e., and attempt to simplify the basics of Trinitarian theology and it’s role in various other areas of theology to make it accessible to many), and is even inspiring. It is very tangential, but much of this can be forgiven. I get it; Fr. Gaitley wants to take advantage of the opportunity he has to supplement people’s general catechesis, which is too often handled very insufficiently. There are times when I think Fr. Gaitley goes a little too far in his simplifications, to the point of too many small technical inaccuracies than I am comfortable with, and the style can use work. Ultimately, what I’m saying is that is just needs to go through a good editing, and then it’ll be great. But for what it is, I found this book to be good enough to recommend to anyone who wants to learn more about the Trinity and the difference the Trinity makes in the Christian life.
Profile Image for Galen G..
40 reviews
February 15, 2018
Fr. Michael Gaitley has a fluid manner of writing that makes difficult subjects easy to grasp and understand. In this book he uses theology and philosophy to lead us through an understanding of "communio", a way of understanding ourselves in relation to God. But it is so much more. As he states at the beginning of the book, the one thing that is needful is the Three -- the Holy Trinity. Then he goes on to unpack what that means. A good, if sometimes difficult, read.
Profile Image for SKP.
1,102 reviews
January 18, 2023
Quite honestly, I did not finish this book. I could see that it was very well-written, but I have very little interest in highly scholarly religious materials. It was too deep for me. I still gave this 4 stars because I saw the potential, and did not wish to take the fact that I’m not all that intellectually inclined against the author. I think if a person is interested in theology, specifically Catholic theology, this would be an excellent resource.
Profile Image for Anna Bieganowska.
67 reviews6 followers
August 14, 2023
I loved this deep-dive into why the Trinity is the love we seek and God (in the Trinity) is always seeking us out, and how to relate that seemingly simple but insane fact to mundane everyday life. I’m always sucked in by Michael Gaitley’s conversational yet intellectual voice and the words he uses from the Bible, saints, and theologians that touch something in my heart of hearts.
Profile Image for Sue.
265 reviews10 followers
October 4, 2024
I read this book very slowly. I would take it with me to adoration once a week and read 8-10 pages at a time. This book is pure gold. Down to earth, easy to understand, heart warming. I’m said that’s it’s done! I’ll be looking for another inspirational book for adoration!!
589 reviews4 followers
March 15, 2020
A great theological introduction to the Holy Trinity. I enjoyed how it is written in a more personal rather than academic style.
10 reviews
January 27, 2023
Ambitious undertaking by Gaitley. Sets out to show how the Trinity explains everything - and is fairly successful!

Very good read for anyone looking for more theological context to the faith.
1 review
February 26, 2024
Very insightful

Opened my eyes and my heart to better understand the Holy Trinity.
I am at peace with my life and look forward to spreading the message to anyone who needs help.
Profile Image for Luke Adamkiewicz.
7 reviews
May 30, 2024
Comprehensive and theologically sound but presented conversationally. Best for an amateur theologian or beginner to deeper Catholic topics.
129 reviews1 follower
August 20, 2023
I love the appendix. Okay, the book is a good read, but the appendix is a guide to other books and best of all gives a shrt dissection of St Thomas' Summa. Gailey covers a lot of ground so hang on!
Profile Image for Amanda.
772 reviews25 followers
July 4, 2013
The book started out very strong; I was quickly captivated by Gaitley's style of writing and I was intrigued with his analogy between the Trinity and a family-interesting take on the Trinity that I had never thought of before, but it makes sense, and I like it.
As the book continued, my attention wavered. It was probably me, not the book, but I honestly don't remember a lot from the middle sections of the book. The end caught my attention again. I would love to find a poster of Gaitley's "Big Picture" which he explains in the conclusion and which is on the inside of the back cover. I tried searching everywhere online I can think of, but no luck.
I also really love the first appendix, in which Gaitley rates each of the books/letters/tapes which he quoted throughout the book. It was well organized and very helpful.
Profile Image for Patricia Mckenna.
46 reviews
October 22, 2015
This is one of my favorite books. The book helps to summarize our Catholic faith and yet gives details that enhance your understanding of hard topics like the holy trinity. The author Father Michael Gaitley does a wonderful job with his illustration of the "Circle of Being". His conversational tone is meant to be like a retreat and it makes it fun and puts the audience at ease. He puts the trinity at the center of understanding our faith. My understanding of the word "communion" has greatly expanded with his description of the trinity's exchange of love. I loved the example of "picturing the pagoda". I highly recommend this book.
1,353 reviews6 followers
September 4, 2016
This is not what I expected and it wasn't really my style. This is not a book about the Trinity, that bit about explaining everything is the key part of the title that I missed. Instead Fr Gaitley uses a triune structure to explain life... it is a bit of a retreat, a bit of theology, and a bit of some other fuzzy things. It was interesting at time, but never really got me. Probably read a dozen books in between starting and finishing.
Profile Image for Bill Breen.
303 reviews5 followers
May 31, 2022
A great book!!! Theology, the Fr. Michael Gaitley way-- very readable and understandable. He covers alot of spiritual ground. Steeped in the Scripture, Catechism and the Saints -- a must read for any Catholic or inquisitive Christian.

Part of Stage 2- Hearts Afire Parish Program. Combines with You Did it to Me by Fr. Gaitley.
Profile Image for Lauren Lutz.
31 reviews1 follower
November 17, 2015
Amazing! Beautiful, thought provoking and mind blowing theology! I will read and re- read this this book for the rest of my earthly life. There is so much to unpack here and I recommend watching the video along with the written word for the first time but wow!!! One of my all time favorite books.
Profile Image for Chad Torgerson.
Author 3 books24 followers
June 5, 2013
Amazing! I had the chance to meet Fr. Gaitley in person, and he is a warm, kind-hearted man.
Profile Image for Jessica Gallegos.
9 reviews
April 30, 2015
Fantastic read regarding the Trinity and how we bridge the gap between heaven and earth. It will take you on a spiritual journey that will enrich your faith and deepen your relationship with God.
Profile Image for Julie.
183 reviews14 followers
August 1, 2021
This book is a straight forward theology book and there's a picture at the end. I enjoyed this one. I like Michael Gaitley books.
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