Why is Giles blamed so much?

When Reverend Hale arrives in Salem to investigate rumours of witchcraft, Giles Corey, probably thinking that he was doing good, asks the reverend to explain Mrs Corey's fascination with strange books. When the reverend tries to tell him that there is no significance in that, he presses the reverend and states that whenever Martha (his wife) reads these tomes, he cannot pray, but that as soon as she stops and walks out, his ability to pray suddenly returns. He states that this oddity 'discomfits' him.

The unfortunate Giles' efforts to save his wife amounts to nothing because he is later arrested for contempt of court for refusing to provide the name of a witness in an accusation against Mr Putnam. He shouts that he had already given up his wife's name and will not allow an innocent to be arrested again because of him. The charge later becomes one of witchcraft and Giles is later pressed to death when he refuses to confess.