Today is Trinity Sunday. Since the end of November we’ve been following the coming, life, death and resurrection of Jesus, with the seasons of Advent, Christmas, Epiphany, Lent, Holy Week, Easter and Ascension. Then last week we celebrated Pentecost, as Jesus bestowed on the disciples the gift of the Holy Spirit. But today’s observance of Trinity Sunday is not about the life of Jesus specifically, but it encourages us to think about the nature of God. We worship God as Father, Son and Holy Spirit.

Three seems to be one of those special numbers that we can’t get away from. Many everyday expressions contain threes: we might say somebody has been taken in by a joke ‘hook, line and sinker’; or verbose politicians might say that they don’t hold to a particular policy ‘in any way, shape or form.’ We’ve all heard of Godilocks and The Three Bears, and the Three Wise Monkeys who apparently see no evil, hear no evil and speak no evil. Something seems to draw us to this number three. Time is divided into three: past, present and future. Three is known as the number of perfection or completion; the number of harmony, wisdom and understanding. It’s interesting that we speak of the Three Kings who visited the infant Jesus at Bethlehem, though the bible doesn’t tell us there were three, only that they brought three specific gifts.

God’s three special attributes are omniscience, omnipresence and omnipotence, but let’s not go there at the moment! Now certain scholars will point to the fact that the concept of the Trinity is not a biblical one, and it is true that the word ‘Trinity’ is not found in the bible. But there is plenty to point us to the presence of the Trinity, and Christians have found it helpful to highlight and celebrate the relationship existing between the Father, the Son, and the Holy Spirit. And this relationship is central to our understanding of God.

In today’s gospel, and in other parts of John’s gospel, particularly, Jesus talks much about this relationship. We heard from Nicodemus, a Jewish leader, who starts off the discussion. He acknowledges that Jesus is a teacher come from God, for, he says to Jesus “no-one can do these signs that you do apart from the presence of God.” And Jesus replies by pointing out that the indwelling of the Holy Spirit is fundamental to anyone who wishes to enter the Kingdom of God. He tells Nicodemus, “No-one can enter the kingdom of God unless born of water and the Spirit.”

There is a wholeness between the three persons of the Trinity that the believer must try to embrace. In the Old Testament reading for today, the one Lord speaks to Isaiah in the first person plural, which we would understand if we knew Hebrew and read the text in Hebrew. But we get a hint of this as the angels cry out, “Holy, Holy, Holy” Lord.

Now no sermon constructed by humans is ever going to unravel the mysteries of the Trinity. But perhaps we can be helped in this quest by considering the members of a family. It is quite possible to find three members of a family with very different personalities. If we try to understand how that family works and gets on, we may not get a true picture if we only know one member of it. Possibly one parent is a very dominant figure, and the other parent is usually seen in a supportive role; possibly a child is inventive. If you looked at one of the parents, you wouldn’t understand how the family lived successfully if you didn’t know that there were other personalities members who offered different gifts and characteristics that together resulted in a rounded family atmosphere, and a unity of love.

So it might be with God, though not in the rather rigid terms in which I have described that family’s life; and part of the doctrine of the Trinity is that what we believe of the glory of the Father, the same we believe of the Son, and of the Holy Spirit, without any difference or inequality. So if we worship only God the Father, whom we often think of as Creator – perhaps the God of the Old Testament with its laws and decrees, we would overlook the human face of God as seen in Jesus, who came to us and walked with us, and showed us how God is fully involved in our lives. Perhaps we would also overlook the activity of the Holy Spirit, always enlivening us, creating new possibilities, bringing good out of bad. We should not forget that Jesus promised the Spirit, and returned to his Father at the Ascension so that the Spirit could be given.

That is why Trinity Sunday follows close on the heels of Easter, Ascension and Pentecost. We have to acknowledge this relationship between Father, Son and Holy Spirit if we are to make sense of the Christian life. Today’s gospel ends with the great statement that “God so loved the world that he gave his only Son…” And the love is shown through the self-giving of Jesus and the indwelling of the Holy Spirit. Love is at the centre of our faith, and of what we understand about God.