Scriptural Interpretations
The distinctive practice of these churches is variously known as serpent-handling, snake-handling, and taking up serpents. Many people consider snake-handling to be a part of uneducated folk religion, however, churches who practice snake handling claim their scriptural mandate from the gospel of Mark 16:9-20. Curiously, this passage is arguably a later addition to Mark, and is footnoted as such in most well known translations of the Bible. Even those denominations who affirm this passage as canonical do not interpret the passage as a call to handle serpents; they regard snake handling as the grave error of "tempting God" and the passage as a statement of signs demonstrating Paul's apostleship (cf. Acts 28:3-6).
Snake handlers argue that it is tempting God when one picks and chooses what parts of Scripture to believe and ignore. They add that Jesus only spoke to Satan who was tempting the Lord. Satan, they argue, asked Jesus to throw himself off of a cliff when he expelled the statement, "Thou shalt not tempt the Lord thy God!". In addition they state that if God himself asked Jesus to throw himself off of the cliff instead of Satan, just as God asked Moses to pick up a serpent without question which then transformed into a rod in the Old Testament, Jesus would have done so. "Fear and the slightest form of doubt" as some handlers maintain can be enough to kill some worshippers which is why they encourage those, who have fear and doubt, not to partake in such practices unless they are living a morally correct life of holiness and total trust in God's Will.
Read more about this topic: Church Of God With Signs Following