The soul “wonders if the whole thing was imagination . . . if the favor was a gift of God, or if the devil was transfigured into an angel of light. It retains a thousand suspicions, and it is well that it should, for, as I said, we can sometimes be deceived in this respect, even by our own nature.” (Teresa of Avila: Fifth Mansions: Chapter One)
We doubt mystical experiences. We question if the “whole thing was imagination”, a “gift of God”, or if the devil was “transfigured into an angel of light”. The soul is wisely suspicious in the fourth Mansions. As we move deeper into the Interior Castle and draw closer to God we can gain certainty our mystical experiences are authentic.
The desire for mystical experiences has led some to foolish and/or destructive behaviors. But the risk of deception has also led others to reject mystical experiences. The “skeptic” believes mystical experiences are a runaway imagination. The fearful call them the work of the devil. The foolish, the destructive, the skeptics, and the fearful all share something in common: They reject the power of our union and intimacy with God.
A deeper union with God reduces the risk of self-deception and marginalizes the devil. Teresa says, “if this is indeed union with God, the devil cannot enter or do any harm; for His Majesty is in such close contact and union with the essence of the soul that he will not dare to approach, nor can he even understand this secret thing.”
Some will always live in fear and doubt about mystical experiences. They are convinced mystical experiences are foolish or dangerous. But being deceived is not limited to mystical experiences. We can be deceived by what we think we see. What we think we hear. Others can deceive us. We can be deceived into thinking actions are justified when they’re not. (In fact, most of our anger stems from intentional self-deception.) Deception is not about whether something is “visible” or “invisible”. Deception results from a lack of wisdom and spiritual maturity.
The formula is simple: Immaturity + Misunderstanding x Distance from God = Risk of Deception
We’ve become over-confident in our ability to interpret the observable world. We dismiss the invisible. That leads to deception.
Jesus Follower, Blogger, Public Speaker. Teresaofavilaturns500.wordpress.com
Teresa of Avila Turns 500 
The balance that is struck here is uncanny. We rarely hear clarification and definition surrounding this much avoided topic. We either feel like our choices are to ‘drink the cool-aid’ or become a fundamentalist.
Eden,
Thanks for adding to the conversation. I appreciate you taking the time to read and comment.
Dave
There is an interesting parallel between the ‘mystical experiences’ in relation to working in the medical field. Many times, we ‘read’ what the patient displays vs reading what we cannot see inside the human body. The deception in that aspect can be minor or major! However, I see this happen more so in end of life experiences in which the patient who is truly now in God’s hands more than ever (in my little world) and the uncanny events that surround the family – and their human attempt to justify the actions of the events and actions of the loved one and the immediate world surrounding them. “We can be deceived into thinking actions are justified when they’re not” is never more obvious than in the final hours of life. But yet God himself displays His power to the survivors while the spirit of the patient is most decisively being controlled by the Almighty. I understand the comments you have posted are written within the context of living souls however I see this time and time again in a precious and delicate environment of end of life.
Thanks for reading and sharing your thoughts Elizabeth. Always good to hear from you.