What is a sacrament?
A. sacrament is a sacred act
B. instituted by God,
C. in which God Himself has joined His Word of promise to a visible element,
D. and by which He offers, gives, and seals the forgiveness of sins earned by Christ.
Note: The word sacrament come to us from the Latin Bible, where it translates the Greek word mystery.
At first this word described all the saving truths of the faith, such as the Trinity, the incarnation, the redemption, the church
(see for instance 1 Cor. 4:1; Eph. 5:32 and 1 Tim. 3:16). Later it was narrowed down to our present sense.
How many such sacraments are there?
By this definition there are two sacraments: Holy Baptism and the Lords Supper.
Why are we to treasure the sacraments, when water, bread, and wine are such common elements?
"The sacraments and all the external things ordained and instituted by God should be regarded not according to the gross,
external mask (as we see the shell of a nut)
but as that in which God's Word is enclosed"
(Large Catechism IV 19)