What is Mysticism...

To many modern Christians, words like "meditation," "mystic," and "mysticism" bring to mind Eastern religions, not Christianity. Certainly Eastern religions are known for their mysticism; however, mysticism is not only a vital part of the Christian heritage as well, but it is actually the core of Christian spirituality. Mysticism simply means the spirituality of the direct experience of God. It is the adventure of "the wild things of God."

The direct experience of God is a kind of knowing, which goes beyond intellectual understanding. It is not a matter of "belief." It is marked by love and joy, but it is not "emotional experience." In many ways, it is better described by what it is not. To describe what it is, we must use metaphors—the marriage of the soul to Christ, the death of the "old man" and birth of the "new man," being the "body of Christ."

Jesus proclaimed "I and the Father are one," (Jn. 10.30) showing the world what the union of God and man can be. Christian mysticism is about nothing else but this transforming union.

Christ is the sole end of Christian mysticism. Whereas all Christians have Christ, call on Christ, and can (or should) know Christ, the goal for the Christian mystic is to become Christ—to become as fully permeated with God as Christ is, thus becoming like him, fully human, and by the grace of God, also fully divine. In Christian teaching this doctrine is known by various names—theosis, divinization, deification, and transforming union.

A common misconception about mysticism is that it's about "mystical experiences," and there are many volumes on such experiences in religious literature. But true mysticism is not focussed on "experiences" (which come and go) but with the lasting experience of God, leading to the transformation of the believer into union with God.
..............http://frimmin.com/faith/mysticismintro.php