If the relationship between Jesus, the God that Jesus called Father, and the Holy Spirit – the Comforter that Jesus promised he would send – is the point of the whole “One God, Three Persons” thing, then what is that relationship? Unity. Not a mere common purpose, but a complete unity of being – with nonetheless separate (but not separated) persons – grounded in Love. If you think about each Person of the Trinity and what each one does, the Trinity not only shows us the Love that made us, the Love that saves us, and the Love that remains with us, it also shows us that these are each and all the same One who Loves us.
Okay, so is this why the Trinity is sometimes called a “mystery”? Yes, but not because it is needlessly complicated or nonsensical. It is a mystery in the sense that there is so much to it, that there is so much more to unpack and so much more that rewards the unpacking, so much more than you can say in A Moment Before Mass. On the way into Mass this weekend, think about what (and Who) the Trinity is, and the Love that is at the heart of the Trinity, and be open as you can to the readings and to the metaphors that you hear in the homily. You just may be surprised at what God does with what you hear.
Readings for Trinity Sunday: http://www.usccb.org/bible/readings/061514.cfm