What is the indwelling of the Holy Spirit?

Anything, which interrupts the natural workings of the life currents in the system is injurious to the indwelling spirit. 

The use of alcohol changes molecular action, arouses the animal nature and the spirit becomes brutish.

If a child is nursed by a wolf and reared in a cave, it will walk on all-fours, and its physical organism will in many particulars resemble that animal. 

The spirit within your body is even more pliable and impressible than the physical organisation of the embryonic child serenely reposing in the mother's womb, and if you wish to brutalise it, arouse your animal nature, and the result you seek will be fully accomplished.

—Lucretus in Spirit