Why 3 Persons in the Trinity?

I work with 7th graders and need to give a response that they can comprehend. The question they asked is “Why is God a Trinity?” They were not looking for an explanation of the Trinity … they were asking “Why” … why does he choose to be three persons in one God? … Why not just one person? Again NOT how but the reason He chooses three rather than one.
They understand the principle and the teaching of the Church as well as a seventh grader can understand. They are simply wondering “Why?”

First of all it is important to point out to the 7th graders that we know the Trinity is three persons only because Jesus reveals it. He teaches that he and the Holy Spirit possess the same Divine Nature as the Father–that’s to say they are equal to the Father.

Now, there is a way that we can apply reason and see the reasonableness of there being three persons and not four or five. You might explain it in the following manner.

God has two faculties (powers)–infinite intellect and infinite will. He uses his intellect to generate or conceive an idea of himself. Because the Father is perfect, the idea that he generates of himself is everything he is except being the Father (or generator). As such, the idea is personal, possessing the same infinite intellect and will as the Father. This is why John tells us in John 1:1, "In the beginning was the Word [idea in Father’s mind], and the Word was with God [distinction], and the Word was God [equality].

So, by starting with the infinite intellect and moving to God’s knowledge of himself we conclude with two distinct persons, the Father (generator or thinker), and the Son (the idea or the thought generated).

Now, there is one other faculty within the Divine Nature, namely the infinite will. The father exercises his will to love the Son, and the Son returns that love with the same infinite will. This exchange of love between the Father and the Son is everything the Father and Son are except being the Father or the Son. As such, this act of love is eternal, personal, infinite, etc. This bond of love is the Holy Spirit.

So, by proceeding from the operation of the infinite will, we can now see the third person of the Trinity in relation to the first two.

Now, ask your students, “Are there any more faculties or powers to be exercised?” No. So, there are three persons in the Trinity because the infinite powers of intellect and will are perfectly utilized in the begetting of the Son and the spiration of the Holy Spirit.

I would encourage you to get a copy of Frank Sheed’s book Theology for Beginners. He gives probably the best popular description of the Trinity.

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