Trinity Sunday is the first Sunday after Pentecost, devoted to the Trinity. It's observed in the Roman Catholic church, the Anglican Communion and all its churches, as well as the Orthodox, Lutheran, Presbyterian and many other denominations. Your mileage may vary about the specifics of vestment colors and so forth, but the commonality is the timing as well as the purpose of the day - namely to celebrate the Trinity.
The Trinity doesn't really seem to be that big a deal until you realize not only is it the sticking point that prevents Christians from being recognized by Judaism and Islam - being fiercely monotheistic they take incredible issue with the notion that there's this whole three, but this whole one thing. The shema, read by Jews the world over, declares God to be one. One of the biggest crimes, and an unforgivable one at that in Islam is "shirk" - namely joining others with Allah. By definition, trinitarian Christians (e.g. most of them) are "mushrik" - those who practice "shirk".
There was a significant amount of literal in-fighting about the whole three or one thing anyway. The early Church dealt with a whole mess of dark midnight catacombs meetings, skullduggery and a few literal backstabbings. The two sides sent mercenaries to torch the churches of the other side and intimidate their parishioners, preferably burning the building to the ground with the priest and congregation inside. In fact, the whole monophysite vs trinitarian argument is why we now look to Rome and the Roman Catholic church, and not Antioch and the Syrian pre-Orthodox church. The entire course of Christian history was influenced by this fight, and the winners and losers thereof. Anyone who even LOOKED like they were "backsliding" away from the Trinity, or giving alternative explanations or different takes on the whole thing were captured and tried for heresy, stamped out as soon as they sprouted up.
It's a big deal.
But try doing a sermon on it. It's the one time of year sermoners hate, and most punt after the first few years of preaching and fall back on either tired cliches of rambling on about shamrocks, and lilies and other symbols of the Trinity - or simply doing the "I hate talking about the Trinity, it's a pain in the ass, is it really that relevant in our post modern age" speech. "Here we are again, and I'm supposed to talk about this, and... uh..... splunge." Nobody wants to start talking in some metaphor that leans into heresy, such as suggesting God appears to us in three forms, as opposed to genuinely being three people, but being one person.
I don't really get the issue here, the Trinity makes a certain amount of sense. God is God, but we understand God through the persons of God.
For God to BE God, God has to be a person who is Lord. Big Chief, Big Kahuna, Head Guy In Charge, Head Honcho, The Buck Stops Here, the absolute ultimate CEO. That bit about being a man sitting on a throne with a beard is taken as metaphor by just about everyone except for people who preach out of a street corner or in a comic book.
But God also has to be personal, and relatable. God's not someone who you grovel in front of and file an end-of-life status report to. Jesus Christ walked amongst us, serving us, and dying for us. Healing us, crying with us, answering our prayer to have mercy on us. That last statement, as understood by the meaning of the language when that phrase was used, amounted to "understand us for who we are and level with us at our level". God is wonderful, infinitely patient and loving, and willing to meet us where we are. That's God the Son. No less a God than the Lord and Master of the Universe.
But God isn't, as a person, just someone of a guidance counsellor and boss. Sometimes a more modern metaphor works better. Master Yoda, in The Empire Strikes Back referred to a force that connects us all, something within us all and without us all with great power, that can be used for good, or for evil. The Greek word used was "pneuma", which means "wind", "breath", and "soul" - and what it meant was pretty much what we'd understand "the Force" to be. There's a joke that you can tell the Episcopalian in the theater at a Star Wars screening - when someone says "the Force be with you", he answers "and also with you". That's LITERALLY what we pray, and I have no issue with the concept being adapted to sci-fi. God's active, not someone sitting around in some celestial Fortress of Solitude watching and writing everything down.
Is God God? Yes. Is God one or more of the above? Yes. Does that mean there are three people? Yes. Are they the same one? Yes.
I diverted from my usual churchgoing today - I saw a beautiful old Presbyterian church on a campus in a sojourn to the east side, and on a whim showed up. I've given some thought to visiting other denominations - not to shop, but to see what others do. In A New Kind Of Christianity, the Emergent Christian author spends a few months in each denomination and shares what he took from each, and I liked that idea so much I spent today elsewhere.
The female pastor, pastoring over a small congregation of alternative characters - gave an intriguing take on today. After doing the whole "I hate preaching about this, I'm not going to, I'm punting just like everyone else does, ha, ha" rap, she began to say that the real value of the Trinity in the postmodern world is to see what you lose if you take one of those persons away, or what alternative persons you'd use. Mother, womb, love? Creater, Redeemer, Sustainer? Love, Lover, Beloved? That was an intriguing take, and one I'd like to share on this important holiday and add to the sermon I'd give if I was ever charged with giving one. Okay, so she referred to Jesus as "JC" and called out to me "Yo!" to arrest my egress when I attempted to leave after the service (was I not staying for lemonade and to meet people?) but visiting that church gave me a valuable insight. Maybe it's not so much the persons we've traditionally ascribed to God, but why we have, and what all of that means anyway. Some preachers think the whole Trinity thing gets in the way of intelligent conversations about Christianity and is nothing more than dogmatic takes on theology, but I have a new light in me right now.
Intriguingly, this was cemented in the doxology. But for the printed service booklet, I'd have given the traditional
Praise God, from whom all blessings flow
Praise Him, all creatures here below
Praise Him above, ye Heavenly host
Praise Father, Son and Holy Ghost.
Instead, we sang (and if they hadn't dipped to the minor accompaniment to the end of the second line, I was damn well going elsewhere later that day to do the Old Hundredth properly!)
Praise God, from whom all blessings flow
Praise Him, all people here below
Praise Holy Spirit evermore
Praise Triune God, whom we adore.
Certainly food for thought. Though the change was meant to eliminate the patriarchal tone of the original, it cast a different light on what amounts to the same thing. All in all, approaching God in the fellowship of an alternative congregation was probably the best way for me to spend the Holy Day assigned to meditating on the multiplicity and unity of God.