It is common knowledge that many clergy struggle to prepare a sermon for Trinity Sunday. It is as if they collectively throw their hands up and say in frustration: ‘The Trinity – it’s a complete mystery to me.’ Well, I guess that is the point: the Holy and Blessed Trinity is a mystery which is beyond the human mind to fathom. Where do you start? Where do you end? God has no beginning and no end. Which is why, as Sirach the sage would say, we need ‘revealed knowledge.‘
Although we speak of the mystery of the Trinity, the word ‘mystery’ does not imply that nothing can be said.
It is, however, a truth that cannot be accessed by reason alone. It is hidden in God and could not be known unless revealed by God. Although the Trinity was hinted at in creation and in Israel’s history, this mystery only became explicit with the incarnation of God’s Son and the sending of the Holy Spirit. Through the Scriptures God progressively and gradually reveals that he is Three Persons in One God, culminating in the sending of his One and Only Son. The secret kept hidden for many ages is that God is God the Father, God the Son, and God the Holy Spirit. When we make the sign of the cross we proclaim our faith in God as Trinity: ‘In the name of the Father and of the Son and of the Holy Spirit.’