Christ for Us

One finds many who say: Christ is the Son of God, born of a pure, chaste virgin. He has become man, has died and risen again from death, etc. All this means nothing. But that He is Christ, that is, that He was given for us, without all our works, without all our merits -- to accept this truth is faith and means recognizing Jesus Christ aright. This is the touchstone, the ruler, and the balance whereby you are to weigh all doctrine. The others do indeed also speak of Christ as the Son of God, as Him who died, rose again from the dead, etc. But these professions are the sheep's clothing. 

Source: Quoted in Ewald M. Plass, What Luther Says, A Practical In-home Theology for the Active Christian.  St. Louis: Concordia Publishing House.  1959 Edition, 10th Printing (1994), p. 198