Religious and secular response to the challenge that 'Neurotheology shows that religious experiences can be simulated through devices such as the God Helmet'.
However, when God chooses to communicate with someone it has to be processed by the brain, so evidence of neurotheology and hallucinogenic drugs doesn't mean that religious experiences are just states of mind.
The mind can also generate such experiences. Spiritual discipline such as those set out in Teresa of Avila's writings train the brain to focus exclusively on God, resulting in mystical experiences.