Enthusiasts and Visionaries...

Enthusiasts, per Luther, are those that do not base their doctrine and practice on the Scriptures, but claim that the Holy Spirit teaches the Church without the necessity of a scriptural norm.

The following quote is taken from the editor's note to Article VIII (Confession) of Luther's Smalcald Articles in The Reader's Edition of the Book of Concord:

Luther never intended to abolish private Confession and Absolution, only to do away with the errors and abuses that had come to be associated with it.  A particularly great abuse was the requirement for a complete enumeration of sins.  Luther insists on the biblical view of God's mercy and grace, which comes by the external, objective, and outward Word.

Radical reformers taught that people should seek God outside of His Word, looking instead to their inner feelings, thoughts, and other so-called spiritual experiences.  (Luther calls them enthusiasts or Schwarmer, a German word for the buzzing of bees).  Many make the same claims today!  This error is rooted deeply in all people as a result of the Fall.

From the article itself:

In issues relating to the spoken, outward Word, we must firmly hold that God grants His Spirit or grace to no one except through or with the preceding outward Word [Galatians 3:2, 5].  This protects us from the enthusiasts (i.e., souls who boast that they have the Spirit without and before the Word).  They judge Scripture or the spoken Word and explain and stretch it at their pleasure, as Munzer did.  Many still do this today, wanting to be sharp judges between the Spirit and the letter, and yet they do not know what they are saying [2 Corinthians 3:6].  Actually, the papacy too is nothing but sheer enthusiasm.  The pope boasts that all rights exist in the shrine of his heart.  Whatever he decides and commands within his church is from the Spirit and is right, even though it is above and contrary to Scripture and the spoken Word. 

All this is the old devil and old serpent, who also turned Adam and Eve into enthusiasts.  He led them away from God's outward Word to spiritualizing and self-pride.  And yet, he did through other outward words.  In the same way, our enthusiasts today condemn the outward Word.  Yet they themselves are not silent.  They fill the world with their babblings and writings, as if the Spirit could not come through the apostles' writings and spoken Word, but has to come through their writings and words.

This is a huge problem across the spectrum of the church today.  This mentality that whatever is on one's heart is paramount.  However, one's thoughts and feelings are completely subjective.  It sounds very spiritual to say that God speaks to us through various means such as our heart, through visions, through dreams, through encounters with people throughout the day, etc., but it is spiritually deadly to do so.  We can be so easily led astray by our emotions or random experiences.  Many of the people I hear who proclaim that we should listen to ours hearts tend to say things that exalt themselves.  They idolize their hearts, their thoughts, their own deeds.  It is as Luther penned:  Self-pride.  To know better than God's Word  that has already been proclaimed is pride.  Peter warns us:

1 But false prophets also arose among the people, just as there will be false teachers among you, who will secretly bring in destructive heresies, even denying the Master who bought them, bringing upon themselves swift destruction. 2 And many will follow their sensuality, and because of them the way of truth will be blasphemed. 3 And in their greed they will exploit you with false words.    2 Peter 2:1-3

A preacher who can stir emotions is considered filled with the Spirit while a sound expositor of Bible truth is considered dead and dry. Emotional enthusiasm becomes the standard by which all religious experience is measured. The Word of God is inconsequential.  The Holy Spirit abides within every born-again believer. He is the believer's Comforter and Teacher. Without question He utilizes the means of inward impressions to direct those within whom He abides. Never, however, does the Spirit of God work contrary to the written Word of God!