Today we celebrate the most astonishiong, mind-bending truth of all: that though there is, and can be, only one God, yet in this one there are three persons. We could never have known that had it not been revealed through Jesus. In the Gospels He speaks of Himself frequently as the Son, sent into the world by the Father; at the Last Supper He revealed that the Holy Spirit would be poured out, as joint gift of Father and Son.
God is mystery; the words we use about God are inadequate. So we speak of three persons in God; they are not persons in just the same way that you and I are persons, otherwise there would be three gods. But it’s right to speak of them as persons because – like us – Father, Son and Holy Spirit are distinct from each other, and relate to each other. Here at Mass, the Blessed Trinity is at the heart of all we do; here – in, with and through Christ, and in the power of the Holy Spirit – we tiny creatures are enabled to give all honor and glory to the Father.