Faith in the Trinity rests on God's revelation of himself in the economy of salvation. We do not have access to the Trinity outside what God revealed to us by sending his own Son and giving us his Holy Spirit. This point is crucial.

The incarnation, passion, and resurrection of the Son do not modify the Trinity. In becoming man, the Son 'enhanced human nature without diminishing the divine.' 'Even when the Word takes a body from Mary, the Trinity remains a Trinity, with neither increase nor decrease. It is forever perfect.