The farther a science penetrates its object, the more it approaches mystery. Even if on its journey it encountered no other object it would still always be faced with the mystery of being. Where comprehension ceases, however, there remains room for knowledge and wonder. And so things stand in theology. Disclosed to us in revelation is “the mystery of our religion”: the mystery of God’s grace [1 Time. 3:16]. We see it; it comes out to meet us as a reality in history and in our own life. But we do not fathom it. In that sense Christian theology always has to do with mysteries that it knows and marvels at but does not comprehend and fathom.
Reformed Dogmatics Vol. 1: Prolegomena (Grand Rapids, Michigan; Baker Academic; 2003) p. 619.