St Augustine writes, "It is one Saviour of His Body, our Lord Jesus Christ, the Son of God, who both prays for us, and prays in us, and is prayed to by us. He prays for us, as our Priest; He prays in us, as our Head; He is prayed to by us, as our God. Let us therefore recognise in Him our words, and His words in us."
On Trinity Sunday, we emphasize the Divine Person of our Savior who has united our human nature to his divine nature, yet always remains true God. Whatever Jesus did on earth, it was God who did it. Even now in heaven, it is God himself who as ascending with our human nature and who lives forever to intercede for us as our priest.
This emphasis on Jesus' divinity is part of what led the US Bishops and the Vatican to change the English translation of the closing portion of the collect for Mass from "...through our Lord Jesus Christ your Son, who lives and reigns with you, in the unity of the Holy Spirt, one God, forever and ever." to "....in the unity of the Holy Spirit, God, forever and ever." Because we are not at that moment affirming that the Father and the Son and the Holy Spirit are One God, but rather professing our faith that this Jesus who lives as our High Priest is truly God, forever and ever.