Called the Divine Mysteries by Faith: Not because they are absent from us, but because they are above our understanding.

"In the second place, they raise in opposition also those statements of the ancients in which they call the Lord's Supper a mystery or sacrament, a mystic benediction, and mystical food.  Likewise, that the body of Christ is present or received in or under a mystery or sacramet.  They [the adversaries] understand a "mystery" as a figure or a sign of an absent reality.  But the ancients called both Baptism and the Lord's Supper mysteries, not with regard to the absence of anything but because they could not understand them with their minds or grasp them with their senses; rather, these sacramets occupied a position far above and beyond the range of the senses and the mind and had to be understoood and judged by faith on the basis of the Word of God alone.

Thus Paul says: "We speak the wisdom of God in a mystery" [1 Cor 2:7], and again he speaks of the dispensers of "the mysteries of God" [1 Cor 4:1; Col 1:25-27]."  Chyrsostom, Homilia 82 in Matthaeum, says: "In the mysteries of Baptism and the Lord's Supper we must not only look at those things which are subject to the senses but we must particularly believe that those things which are taught us by the Word are present and bestowed upon us, even though to the senses and to reason they seem absurd, for they are above our senses and our reason."

-Martin Chemnitz