Excellent analysis. I think your historical explanation is important- not the totality of the situation, but important.
Problems with psychotherapy-
1) What are the goals? and
2) "I like what is happening" is a valid reason to consider it successful.
Having to answer 1) above is not that unusual for a scientific endeavor.
The utter subjective nature of 2) above makes it very unusual for a scientific study.
Not all theists believe in 'talking snakes'.The non-existence of 'talking snakes' as an argument against theism would be a 'strawman'.