Karen asks why we call it “the mystery of faith” when we declare in the Mass “Christ has died, Christ has risen, Christ will come again.” Those three declarations are so obvious how can they be a mystery?
Typically we think of a mystery as something that is a secret or that can be understood if we are given enough clues, like solving a murder mystery. But when the word “mystery” is used theologically it means a truth that is revealed and that we accept by faith, such as the doctrine of the Trinity. It is not a truth that we have come to by natural reason or by scientific method. We see the Trinity revealed throughout Scripture but it is not a truth that our minds fully comprehend. Without the revelation of Holy Scripture man would not begin to embrace the Trinity but because of it we worship God in Trinity of Persons and in unity of Being.
It is noteworthy where in the Mass we make our declaration of the mystery of faith. It comes after the prayer of consecration and so we declare the One who is present and whose Body and Blood are veiled in the bread and wine.