Friends, in today’s Gospel, Jesus declares that “the Father and I are one.” Jesus appeared two thousand years ago and announced that he had been sent by the Father. There was a strange “something more” regarding Jesus, for he spoke and acted in the very person of God.
The first Christians had to come to grips with this strange duality: somehow Jesus was Son of God, both sent and divine. He was other than the Father, but somehow at the same level as the Father. Things got more complicated when the Holy Spirit came upon them.
Therefore, there seemed to be a Father (the one who sent Jesus), a Son (the one who was both sent and God), and a Holy Spirit (the divine one whom both the Father and Son had sent). Three but yet all the one God of Israel.
We invoke the Trinity when we make the sign of the cross. This juxtaposition of Trinity and cross is by no means accidental. For the cross is the moment when the tensive unity of the three divine persons is on most vivid display.