Early 20th Century Proto-blogger G.K. Chesterton on why the triunity of the Godhead is important to, well, everybody.
The barren dogma is only the logical way of stating the beautiful sentiment. For if there be a being without beginning, existing before all things, was He loving when there was nothing to be loved? If through that unthinkable eternity He is lonely, what is the meaning of saying He is love? The only justification of such a mystery is the mystical conception that in His own nature there was something analogous to self-expression; something of what begets and beholds what it has begotten. Without some such idea, it is really illogical to complicate the ultimate essence of deity with an idea like love.
He takes a swipe at Judaism with his “the grey deity of the Pharisees and the Sadducees” comment. Of course this is an unfair criticism. God in Judaism is loving, compassionate and very much personally, emotionally invested in his people. There is just little in Judaism on how to sensibly reconcile these attributes of God to the ineffable and transcendent nature of Hashem, or in other words, how God is going to “dwell among his people” in some real, tangible manner. The Yeshua gospel, featuring the Oneness of Father and Son, is the most elegant answer to this conundrum.