This Sunday is designated as Trinity Sunday in many Western churches. It is not that these churches forget about the Trinity the other 51 Sundays of the year (well hopefully it’s not like that.) This day is just set aside to lift up the Christian understanding that we worship one God who is three persons: Father, Son, and Holy Spirit.
Doubtless, there will be lots of sermons devoted to the Trinity. The problem that troubles many of these sermons is trying to explain the Trinity; say too much and it is easy to go beyond the official teaching of 3-in-1, say too little and you might end of with just one being, say too much and you might end up with three unrelated beings.
Saint Augustine realized this danger years ago. In his book on the Trinity, Augustine first surveys the works of other early theologians on the Trinity. Augustine notes that many struggled when they ventured to explain the Trinity. Often they made the Trinity sound like a mathematical problem: 1+1+1=1 Augustine saw the Trinity not as a mathematical problem to be solved but as a model of Christian living.
For Augustine, the Trinity is a model of how Christians are called to live int he world. The Trinity is the original unity in diversity. For Christians, devoted to worshipping and following the 3-in-1 God, the Trinity calls us to live in fellowship with God and neighbor.
Arguments from the days of the early church about how many persons and whether or not they were all one same essence, were not esoteric hair-splitting just to get the doctrine correct. Doctrine was seen as guidelines, stage directions for living the Christian life.
The Trinity is about how we see and understand God, but like Isaiah (Isaiah 6), our vision of God leads to a new way of living in the world. A trinitarian understanding should lead to a trinitarian lifestyle. Such living places us, like Isaiah, before the holiness of God. Here we see our solidarity with others, “I am a person of unclean who lives in the midst of a people of unclean lips.” Yet cleansed by God, we are sent forth to share with others the what God has made known to us, with our lives as well as our lips.