Most people, including Christians can agree that this was an insane act. But while Christians are calling him crazy, many of them consider the Bible to be the LITERAL WORD OF GOD. And this "literal word of God, in the Book of Revelations states:
"If anyone worships the beast and his image and receives his mark on the forehead or on the hand, he, too, will drink the wine of God's fury."AND
The book of Matthew also contains the passage: "And if your right hand causes you to sin, cut it off and throw it away. It is better for you to lose one part of your body than for your whole body to go into hell."
This story reminds me of the book I am reading "I Know This Much Is True" by Wally Lamb, about twin brothers and one of them is suffering with schizophrenia. At the beginning of the novel, the sick, Bible- obsessed twin cuts his own hand off at the public library. I don't think the guy in Idaho got his idea from Lamb's book. He got the idea from his "divine" word of his god. He believes in the Bible...literally.
Good thing most Bible literalists don't take all of the Bible literally.