Why Do So Many Christians (and Christian Churches) Reject Esotericism and Occultism?

The following question arrived in my email inbox the other day…

Why is there such a condemnation in the Christian churches for esotericism/occultism? I have my entire adult life ( I am now 63) been living and working in Anthroposophical circles, I have friends in the Rosicrucian movement and I am impressed with the wisdom of some Theosophical writers. I can say with my hand on my heart that these movements draw the best of sincerely good willing people who wish to cultivate a living relationship...