Scripture must interpret scripture but sadly this is not always the case.
Mark Randall “Mack” Wolford believed that the Bible mandates that Christians handle serpents to test their faith in God — and that, if they are bitten, they trust in God alone to heal them.
He and other adherents cited Mark 16:17-18 as the reason for their practice:

“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 their hands on the sick, and they will recover.”
“I am looking for a great time this Sunday,” he wrote May 22 on his Facebook page. “It is going to be a homecoming like the old days. Good ’ole raised in the holler or mountain ridge running, Holy Ghost-filled speaking-in-tongues sign believers.” “Praise the Lord and pass the rattlesnakes, brother.”

Wolford, the son of a serpent handler who himself died in 1983 after being bitten, was bitten by a rattlesnake during the homecoming and died.

"I marvel that you are turning away so soon from Him who called you in the grace of Christ, to a different gospel, which is not another; but there are some who trouble you and want to pervert the gospel of Christ." Galatians 1:6-7