Aah - the most frightening Sunday of the year for preachers - how to condense all our wonderings about the Trinity into a manageable length of sermon? Well, I think I gave up that a few years ago, and instead go for a 'one facet of a very complicated thing' approach instead.
Isaiah 6: 1-8
Romans 8: 12-17
John 3: 1-17
Wow! Any one of those readings is a big 'chew' theologically speaking...
So, thoughts so far: at one church I have a baptism, at the other the ordination of an elder - but I think in both cases I want to focus on what the Trinity tells us about the God who is relationship - both within the Trinity & reaching out to include us.
Baptism teaches us about our place in the family of God.
The Isaiah reading speaks of a God of awe and power, who nevertheless reaches out to humanity with God's word.
So how do we relate to God, as part of the family?
Jesus makes it clear to Nicodemus that this is a gift, not an earned right. The phrase we usually translate 'born again' can also be translated 'born form above' - in either case, it is not a work of our doing. It is God's will that we should know God 'God so loved the world he sent the only son...' - God in Trinity reaches out to embrace and love the whole world.
Then Romans speaks of the spirit of son (and I want to say daughter)-ship, of adoption. The Spirit leads us more deeply into a pre-existing truth, what is alread tru, even if we do not know it - that we are children of God.
We are included in the relationship at the heart of God in Trinity, to be loved and cherished and to grow.