The Gospel at Mass shed some light on the relationship between God the Father and God the Son.
From John Chapter 3:
God so loved the world that he gave his only Son, so that everyone who believes in him might not perish but might have eternal life.
For God did not send his Son into the world to condemn the world, but that the world might be saved through him.
Whoever believes in him will not be condemned, but whoever does not believe has already been condemned, because he has not believed in the name of the only Son of God.
Over at Whispers in the Loggia, Rocco found a song clip both appropriate and chill to accompany his Trinity Sunday post. I've put it in the audio slot at top right.
The image above is a photo from Waldie's World. It shows the stained-glass window in the Father Judge Memorial Chapel at the Missionary Servants of the Most Blessed Trinity motherhouse in Philadelphia.