intersubjective mysticism

A followup, sidepoint that sprang to mind while writing the last post.

If we take the modernist, materialist view of mysticism (God=Brain Chemistry) and reduce all experience (mundane and/or mystical) to physiology then why does the content of such experience mimic one's own religious, cultural heritage?

In mystical experience, why do certain Christians and Buddhists, whose religious traditions allow for even promote iconography (e.g. Eastern Orthodox, Roman Catholic and Mahayana and Vajrayana), have such iconic subtle mysticism while traditions that do not, e.g. Islam, have subtle mystical experience without iconography? (Or even forms of Christianity and Buddhism that do not accept iconography, i.e. Reformed Calvinist/Baptist Xians).

How does a brain know it should be a Christian brain? Or Buddhist? Or Neo-Pagan? Or fill in the blank.