Trinity Sunday is fraught with peril for the preacher who would try to "explain the Trinity". I attempt it so very rarely and whisper when I do because I accept that the triune personage of God is a Holy Mystery, not meant to be explained or fully known in this life. I accept that the richness I enjoy in my relationship with the Divine is made more deep, more broad, more beautiful by the distinct yet coequal personages in whom God reveals Godself to me and I am pleased simply to experience it all.
Luckily for me, today's Johanine Gospel yields up something entirely easier to preach on.
I am willing to bet that, if you have memorized any scripture at all, John 3:16 "for God so loved the world that He gave His only begotten Son that whosoever believeth in Him should not perish but have eternal life" is among the verses. John 3:16 is seemingly everywhere, referenced in popular culture, songs, films, held up on placards at super bowl games, it is really indelibly set in the collective western conscience as definitive of the Gospel. And this is, by and large, good. I say by and large because of course it is life-giving to know that God loved the world so much that God entered it to redeem it with God's very own life. What is not so good is how the latter half of the verse is often used by well meaning but errant people to threaten folks into believing "So that everyone who believeth in Him should not perish...". This "turn or burn" style of evangelism has done more damage I think than any good. It certainly has not furthered a Gospel of Grace in the world. From the time that I memorized John 3:16 in my early twenties to today, here at 50 I have learned that people cannot be threatened into love. People cannot be scared into accepting grace. The gospel cannot ever be used as a stick.
That is why today I am proposing that we all memorize John 3:17
Indeed, God did not send the Son into the world to condemn the world, but in order that the world might be saved through him.
Now there is a verse that communicates the mystery of God's love for the creation. There is a verse that just says what God is about. It does not prompt us to make a decision, it doesn't cudgel us into committing to a team, it doesn't invite us to judge others as somehow less than ourselves...it just proclaims the Gospel.