The fact that God is three Persons is something we never could have known unless he chose to reveal it to us. It is the very inner life of God, which he has deigned to share with us out of love for us and so that we may love him more deeply in return. After all, how can we love God more completely unless we know him as intimately as is possible for finite human beings? Remember that whenever you are tempted to reduce God to a theoretical abstraction irrelevant to your life.