When I was younger, I would here the word "mysticism" bandied about so much that I came to some rather incorrect conclusions regarding to what the word refers. From context alone, one might conclude that it is only about magical thinking, or being fooled to believe in one religion or another. At this stage of my life I have become convinced that a deeper more historically founded meaning of the concept is needed.
Part of the confusion is the way moderns sometimes want to define and describe God. "He" is seen as having very human qualities, a man with a white beard who in the past constantly interfered with historical processes. A being who operated beyond the constraints of physics. One who could break the laws of physics at will because "He" made those laws.
Yet, this is a very limited, very narrow view of God. In fact many theologians of the past explicitly reject or at least did not stress these aspects of God. For some of them, an encounter with "God" could be a very terrifying experience, hence the phrase "God fearing."
Mysticism is often tied into a belief in God. Yet, I would argue that it is not dependent upon a belief in God. It has its own legs so to speak. It points to something like the Tao in ancient China. Followers can be too busy using the Tao to argue about whether it exists. Mystical experiences can be the same way. They can point to a psychological reality that cannot be doubted. It is only in trying to utilize language to describe a mystical experience that profound error can and does creep in. Indeed, a common theme among mystics of many different religions and philosophies is that mysticism points to something beyond language. It points to powerful emotional experiences for which language can do no justice.
Theologians and philosophers often write of mythos and logos. To try and understand the mystical experience through language is to try to understand mythos through logos. By its very nature, it is doomed to failure.
What perhaps may not be doomed to failure is to understand how the human mind works. Specifically, the role of symbolism. Here, we can look at the mind the way Freud examined our dreams. In our dream state, the mind often contemplates the world through symbols. Some times a cigar may just be a cigar, but more often the images in our dreams constitute a sort of language of symbols. A sometimes garbled language that we can only partially comprehend in our waking state.
Symbolism - the use of metaphors, similes, and parables, can be thought of as a process by which we utilize knowledge of something that we think we understand, and apply that knowledge to something that may be just beyond out grasp. We use this symbolism both for our own understanding and to communicate with others. We say that an electron revolves around the nucleus of an atom implying that there is something similar in that to the way planets revolve around the sun. Christ, in his teachings, made heavy use of parables to illustrate lessons he wanted to teach about basic truths in our lives. One does not need to believe in His divinity to appreciate the wisdom wrapped up in some of those lessons.
Language used in describing the results of mystical revelation can function on the same way. Still, such language is prone to misuse and misinterpretation. So, through the ages observer after observer has described deep mystical encounters that they have had in their lives. Such descriptions were often made in accordance with particular customs and understanding peculiar to the person making the description. So much so that plenty of room for argument and doubt emerged. History has been a process of emphasizing the differences between these states of revelation, while a comparative few have noted striking similarities.
If there is to be a future for mysticism, it is perhaps lodged in a better understanding of those similarities, and in overcoming differences that often emerge. In that, there is plenty of room for science to co-exist. In fact, science merely helps to enrich language and thus helps us to creep forward in our understanding of shared insights concerning the more profound truths of the world. For some, this may seem a hopelessly utopian endeavor. Yet nowadays, mere human survival into the future can also seem like a doomed utopian endeavor. The alternative would seem to be despair and a collapse into cynical selfishness. A collapse that leads nowhere.