The Simple Catholic Snapshots:
- There is only One God
- God is Love
- A Lover needs a Beloved, therefore there are at least two Persons in One God
- Love is Perfected when it is Given in Complete Self-Sacrifice
- God’s Love is Perfect
- Therefore, there are Three Persons in One God, Each Giving Perfect Self-Giving Love to the Others
The Simple Catholic Truth:
Perhaps no other dogma is so fundamental to Christianity, yet remains such a profound mystery as the Holy Trinity. Scripture is clear, there is one God. Scripture is also clear that God is revealed to us as God the Father, God the Son and God the Holy Spirit. But how can this be? How can 1 equal 3?
Brilliant philosophers and theologians have been debating the Trinity for two thousand years trying to define God’s nature and pinning down what exactly is meant by a “person.” These writings are interesting at times, challenging to be sure, but for now I’ll just use the term “person” without getting bogged down in defining it. In this post, however, I’m would like to look at just one narrow aspect of the Trinity and that is: “Why Three?” Why is it necessary that God revealed himself as three persons?  Why not one? Why not four or more? I will present these ideas as plainly as possible but will also include a sequence of graphics as learning tools.
To get started, recall that Holy Scripture reveals that there is only one God. I’ll retain the familiar Christian terminology and refer to this God as a person that we call ‘Father’. We will graphically represent the person as a circle, and the name of this person is Father as shown below.
Ok, so far so good. Using this graphic as a reminder, we now have One God and One person (called Father).
Next, we find in Scripture (1 Jn 4:8) an additional revelation that God is Love. St. Augustine reasoned correctly that every Lover must necessarily have a Beloved. In other words, if a person is Love, then there must be another person to participate in that Love. We can now update our graphic to match our evolving understanding of God.
In this diagram we now have the second person needed to participate in and fulfill the Loving nature of the Father. We refer to this second person as the ‘Son’, or more specifically Jesus Christ. Scripture tells us that the Son shares the nature of God the Father (e.g. eternal, Loving, all powerful etc.) and is therefore also God. We now have One God and Two Persons (called Father and Son).
But Scripture also refers to another aspect of God that is called the Holy Spirit. We now must reconcile the existence of the Holy Spirit with our understanding of God as represented by the above diagram. St Augustine tries to include the Holy Spirit at this point by suggesting that the Holy Spirit is in fact the Love between the Father and Son. I have updated the diagram to include his idea:
But take a careful look at the above diagram. Yes, the person of the Father and the person of the Son exist in proper loving relationship, and the Holy Spirit is included, but here the Holy Spirit is not a person. In this version of understanding, the Holy Spirit is an artifact of the relationship between Father and Son and not a co-equal person as the Bible indicates. Something is still missing.
The step the resolves this dilemma gets a little tricky but stay with me and it will make some sense when we finish. Richard of St. Victor suggests that in the loving relationship between Father and Son shown above, the Love between the Father and Son is not perfect because that Love is not an act of complete self-giving. In other words, the Love of the Father to the Son can not be returned in kind by the Son to the Father. If this dual, two-way nature of love were true, the Father would be ‘getting something in return’ and this violates the idea of perfect self-giving Love. The only solution to this logical dilemma is for the Father to will (for the good of the Son) that the Son have a loving relationship with another. This of course requires a third person that we refer to as the Holy Spirit and is shown (partially) in the diagram below:
Take note that the Love from Father to Son is now perfected by the Love of Son to another (Holy Spirit). Since God is Love and God is perfect Love, His love must be perfected in this manner which includes a third person.
A few quick comments are absolutely necessary before the diagram is completed. We must understand that the Father, Son and Holy Spirit are equal persons, are equally eternal, sharing equally the same nature as ‘God’. In the above set of diagrams, I showed a sequence that started with the Father, then to the Son and then to the Holy Spirit but we only used this sequence for initial simplicity. In actuality, the Love of any of the Persons of God towards the other Persons is equal, simultaneous and interdependent. This leads us to the final version of the diagram which I believe best represents an understanding (although still imperfect) of the Trinity based on the idea that the essence of God is perfect self-giving Love.
Here we see that the Holy Trinity is One God yet Three Persons formed together and united by perfect inseparable Love. The Holy Trinity is logically necessary because of the perfect self-giving nature of God. In other words, perfect Love requires three!
Of course, the explanation above is lacking. No group of words or diagrams can adequately describe God. The Trinity remains a mystery and will be so until He completes the final revelation. In the mean time, try to see God as three Persons of perfect Love.
When we see God in this light, the entire Gospel message including the sacrifice the Cross becomes more clear. We have no greater example of total self-giving Love than the Trinity.
 The ideas in this post are derived in part from the writings of a 12th century theologian, Richard of St. Victor (died A.D. 1173.) In his classic work De Trinitate, Richard explores the mystery of this Christian dogma using a systematic reasoned approach blended with classic philosophy.