"And 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; they will lay hands on the sick, and they will recover.” (Mark 16:17-18)
Following the words of Jesus in the verses above, the Christian can’t be poisoned. It makes no difference how the poison is administered. Why is this so?
"For the life of the flesh is in the blood..."
When people are poisoned, the poison gets into their system through the blood vessels to wreak havoc.
However, being born again, and having received the Holy Spirit, your body doesn’t live by blood anymore. The life of the flesh, for the unregenerate man, is the blood, but now that you’re born again, Christ is your life (Colossians 3:4).
Remember, when Jesus was crucified, while He was on the Cross, a soldier thrust a spear through His side, and the Bible records that blood and water gushed out, because His heart had ruptured. When God raised Him from the dead, there was no blood in His body. The Holy Spirit became the life of His physical body.
"But if the Spirit of Him who raised Jesus from the dead dwells in you, He who raised Christ from the dead will also give life to your mortal bodies through His Spirit who dwells in you."
The day you received the Holy Spirit, He quickened your physical body. He became the life of your physical body. Your life doesn’t depend on blood anymore.
Understand this: anything that affects or destroys the blood can’t, and shouldn’t have any effect on you. This is what we mean when we say the Christian can’t be infected or isn’t susceptible to any kind of sickness or disease. The same Spirit that raised Jesus from the dead has vitalized your body such that no infection can survive or thrive in your body.
The Holy Spirit perambulates in you to see to it that you’re in perfect health, warding off any anomaly that may or could occur with your physical body (2 Corinthians 6:16). Hallelujah!
I'm vitalized by the Holy Ghost! No sickness, disease or infirmity can thrive or survive in my body. The divine life of God is at work in me, in every fiber of my being, in every cell of my blood, and in every bone of my body. I'm alive and well, healthy and strong forever, by the Holy Ghost. Hallelujah!
Further Study: Romans 8:10; Luke 10:19