God chose to show Himself to the people of the Old Testament as the one, true, and personal God. Noah, Abraham, Joseph, David, Daniel, and all of the people of the Old Testament learned that God was real, that He was faithful and true in all His words and actions, that He loved them as a father loves his son, …

The mystery of the Holy Trinity is that there is in the one, true God only one divine substance, yet three divine Persons: God the Father, God the Son, and God the Holy Spirit. The Trinity is called a mystery of faith because it is a truth that cannot be known unless it is revealed by God, and it is …

We believe in the mystery of the Holy Trinity because God revealed it; He is all-wise and all-truthful. To better understand, as best we can, the mystery of the Holy Trinity, we must await God’s unveiling of Himself in Heaven.