Yesterday was Trinity Sunday, following close upon Ascension (the incarnate Son taking His place in the Godhead) and Pentecost (the Holy Spirit poured out upon the Church).
Do you want to know a good Scripture verse to prove the doctrine of the Trinity? “God is love” (1 John 4:8; 1 John 4:16). Love is a union of distinct persons. If love is at the essence of God, then He is a union of distinct persons, only supremely so–a perfect, absolute union of the three persons: Father, Son, and Holy Spirit.
Having a Triune God is very different from having a god of other kinds of monotheism.
I remember reading G. K. Chesterton on the Trinity, who makes this point in an unforgettable way. I dug up a couple of his quotations on the subject, which you can read after the jump.
By Emeltet (Own work), Eglise Saint-Samson, Bobital, Côtes d’armor, France, La Trinité, rosace, facade ouest, [CC BY-SA 4.0 (http://creativecommons.org/licenses/by-sa/4.0)], via Wikimedia Commons
“If the moderns really want a simple religion of love, they must look for it in the Athanasian Creed. The truth is that the trumpet of true Christianity, the challenge of the charities and simplicities of Bethlehem or Christmas Day never rang out more arrestingly and unmistakably than in the defiance of Athanasius to the cold compromise of the Arians. It was emphatically he who really was fighting for a God of Love against a God of colourless and remote cosmic control; the God of the stoics and the agnostics. It was emphatically he who was fighting for the Holy Child against the grey deity of the Pharisees and the Sadducees. He was fighting for that very balance of beautiful interdependence and intimacy, in the very Trinity of the Divine Nature, that draws our hearts to the Trinity of the Holy Family. His dogma, if the phrase be not misunderstood, turns even God into a Holy Family.”― G.K. Chesterton, The Everlasting Man
Unitarians (a sect never to be mentioned without a special respect for their distinguished intellectual dignity and high intellectual honour) are often reformers by the accident that throws so many small sects into such an attitude. But there is nothing in the least liberal or akin to reform in the substitution of pure monotheism for the Trinity.
The complex God of the Athanasian Creed may be an enigma for the intellect; but He is far less likely to gather the mystery and cruelty of a Sultan than the lonely god of Omar or Mahomet. The god who is a mere awful unity is not only a king but an Eastern king. The heart of humanity, especially of European humanity, is certainly much more satisfied by the strange hints and symbols that gather round the Trinitarian idea, the image of a council at which mercy pleads as well as justice, the conception of a sort of liberty and variety existing even in the inmost chamber of the world. For Western religion has always felt keenly the idea “it is not well for man to be alone.”
The social instinct asserted itself everywhere as when the Eastern idea of hermits was practically expelled by the Western idea of monks. So even asceticism became brotherly; and the Trappists were sociable even when they were silent. If this love of a living complexity be our test, it is certainly healthier to have the Trinitarian religion than the Unitarian. For to us Trinitarians (if I may say it with reverence)—to us God Himself is a society. ~ G. K. Chesterton, Orthodoxy