I have often said that there are two kinds of faith. First, a faith in which you indeed believe that Christ is such a man as he is described and proclaimed here and in all the Gospels, but do not believe that he is such a man for you, and are in doubt whether you have any part in him and think: Yes, he is such a man to others, to Peter, Paul, and the blessed saints; but who knows that he is such to me and that I may expect the same from him and may confide in it, as these saints did?
Behold, this faith is nothing, it does not receive Christ nor enjoy him, neither can it feel any love and affection for him or from him. It is a faith about Christ and not in or of Christ, a faith which the devils also have as well as evil men….
Such a faith will work in you love for Christ and joy in him, and good works will naturally follow. If they do not, faith is surely not present; for where faith is, there the Holy Ghost is and must work love and good works.
[Martin Luther, sermon, “First Sunday in Advent,” on Matthew 21:1-9, in John Nicholas Lenker, ed., Sermons of Martin Luther, Volume 1, (Grand Rapids, MI, USA: Baker Book House, reprinted n.d.), 21-22.]