I would bet most of us would say that they haven’t spent much time thinking deeply about the trinity, we could not explain it and we are not sure it would be important to do so. I would suggest 3 reasons why it is important:
We have the moral responsibility as image bearers, to live in reality, to recognize reality, to live in parallel with reality. If God is truly one God, in three persons, and that that God created the universe, and gives us life and secures our future and that God is who we are to relate intimately with, then we must figure out how to live into trinitarian reality.
The triune God perfectly demonstrates, models, and illustrates for us certain truths that we cannot find anywhere else.
The trinitarian God is simply biblical truth and we must be those who are committed to and submit to the authority of scripture.
We’ve talked about how crucial John 13-17 is to much of our faith—and this is the section that is also fully trinitarian—Jesus himself teaches us about the nature of the trinity in John 14. In verses 1-7, Jesus says that he is how we know God the Father. In verses 8-14, Jesus has equated himself with the Father and demonstrates an utterly unique and intimate relationship with God. In verses 15-21, Jesus creates an imagination for the third member of the trinity—the Spirit—as crucial to how we know and love the Father and the Son and how they love us. Finally, in verses 22-26, Jesus receives his teaching from the Father. When Jesus is gone, the Father will send the Spirit; the Spirit will remind the disciples of all the words of Jesus.
Note the distinct personhood of all 3. They are all different from each other. Note the distinct relationships of all 3. There is a mutuality, a love, a sharing between the 3. Note the distinct roles of all 3. They all work together for a common cause. Finally, note the unity of all 3. They demonstrate what true community can be.
So, we must ask ourselves why the trinity matters.
Before creation, and, from all eternity until this very day, the trinity exists in perfect community; reciprocity, mutuality, and love flowing endless from each member to the other. For this to occur, trust has to exist at the kind of levels almost unimaginable to us as humans. When this kind of trust exists, two things are possible—intimacy and commonality of purpose. Flowing out of this perfect community is life and love; they share with the universe what they themselves have with each other. This means that as we begin to know the trinity, we begin to truly live.
In the final section of John 14, Jesus speaks of shalom—fullness, prosperity, flourishing. When you are bathed in trinitarian reality, you are able to live in God’s shalom. When Jesus gives his peace, he never takes it back. That is how his giving is different than the world. That means right now, Jesus has asked the Father, and he has given you the spirit, and by the Spirit you are now able to live in and from God’s shalom.