Certain persons are reguided by their own self as injactions to specific acts or worship -
Which include anointing, drinking poison, faith-healing, testifying, speaking in tongues and handling poisonous snakes.
The text that inspires one group of falling those churches, is from the book of Mark:

"These things shall accompany them who believed and in My name they shall cast out demons, they shall speak in new tongues, they shall pick up serpents, and if they drink any deadly thing that would outherwise hurt them. They shall lay hands on the sick, and they shall recover."