You cannot work effectively for Christ unless you are willing to take a few risks, and Jesus warned his followers that there would be the risk of encountering serpents.
I think it is significant that the Bible calls Satan “that serpent of old” (Revelation 12:9, NKJV), and Jesus said, “Go out into the highways and hedges, and compel them to come in, that my house may be filled” (Luke 14:23), but in Ecclesiastes, we are warned: “…whoso breaketh an hedge, a serpent shall bite him” (Ecclesiastes 10:8, KJV).
Christ promised, however, that “These signs will follow those who believe: In my name they will cast out demons; they will speak with new tongues; they will take up serpents; and if they drink anything deadly, it will by no means hurt them” (Mark 16:17-18, NKJV).
I say this kindly, but the Bible says that the wicked are like poisonous serpents, and we must be snake handlers. This verse in Mark may refer to a missionary or other believer accidentally imbibing a poison, but there is a far greater meaning hidden in this Scripture. Just as surely as Christians drink of the blood of Christ — the river of life, divine love and beauty — we unconsciously also drink of the poison of this world when we go out to preach the gospel.
We absorb so much of the spirit of this world, and we take such deadly things into our spiritual lives that unless we receive Holy Ghost protection, I do not see how Christian workers can go where sinners are. You cannot help drinking in some of these unmentionable things into your spirit, but if you drink any deadly thing while you are going after serpents in the power of Christ, their poison will not hurt you.
When the Lord began to show me this truth, I would go home and pray, and I could feel the breath of the Holy Spirit pouring through my system. The poison would just drain out, and I could stand up cleansed and unharmed.