When Paul was on Malta, he was bitten by a snake, but “did not suffer any ill effects”, and “cast it off into the fire”. Sin is represented by the snake, the serpent, as in “…the sting of death is sin, and the power of sin is the law”.
Sin not only is an operation which is not of God, but is seen as that which brings death, it also provides ammunition for the voice of accusation.
The inference here is that Paul was protected from the effects of sin, because he was a Christian, he had the Holy Spirit, and the poison of sin had no power over him. [he could cast off temptation and guilt into the fire of the Spirit]]
This goes back to the “serpent trail” through scripture beginning with Adam. Adam sinned and wore the effects of that, which was spiritual death followed by actual death. There were the serpents in the wilderness killing the Israelites as they followed Moses, or rather, because they interrupted their following. When they raised the serpent on a pole, and they looked upon it (the reality was there, they could not disbelieve it) they lived. Then Jesus was raised on a “tree”, becoming the serpent once again and representing the sin that caused death. “He became sin for us”.
Jesus took sin and death for us – those who believe have eternal life – the normal rightful outcome of the poison of sin is death, but “there is forgiveness with him”. Jesus has taken the effects of sin and death and abolished them. Faith in him enables the believer to ignore all the accusations that arise from the past, and to grasp the life he offers, which is himself, and to take full advantage of his mercy in revealing to us the magnificence of the life we can have in him.
Normally the sting of sin would damage us, be detrimental to our wellbeing, our conscience and our liberty of will. But Jesus has removed the penalty, the result, of sin, in his own body, so we can be free of both it and the accusations arising from it.
Jesus then, is the antidote to the poison of sin. And he brings us this antidote gently in the person of himself as the Spirit, that he might administer it to our hearts. As we continue with him, he nurtures us and restores us from the effects of our past life, gradually conforming us to his image, and perfecting us in himself. Not that we are not already perfect in the eternal sense, but there is an ongoing process of conformity and growth which needs his continuing presence to administer.
He is the antidote for sin, administered lovingly, though at times it might not taste very nice! But those who do not take this medicine will not be healed. Will not be cleansed. Will not be saved. When the medicine comes in its full powerful sense, its full powerful effect will not heal, but will harm. Jesus was the moderator and go-between between the fire of the Spirit and ourselves. As a gentle antidote, the poison became the cure, the active ingredient of it was rendered impotent, it was an inoculation of sorts. But administered in full potential all at once, the result on a person not so inoculated, will be devastating.
When Jesus returns, his fiery presence will burn away sin, and if the person has no identity outside himself, he will be totally destroyed by that fire which is the Spirit.