Harsnett is noted for his sceptical attitude towards demons and witchcraft. As the chaplain to Bishop Bancroft, Harsnett was commissioned to write a treatise condemning the 1590s exorcisms of
John Darrell, having sat on the 1598 commissions which investigated his activities. was a polemical piece intended to discredit Darrell's puritan agenda. It was drafted as a piece of political propaganda, but it also genuinely questioned the belief in demons. In this way, Harsnett sought natural explanations for supposedly supernatural phenomena. In 1603, he wrote another book,
A Declaration of Egregious Popish Impostures, published by order of the
Privy Council, Harsnett was a strident anti-
Calvinist. The extent of his
Arminian theology has been discussed by historians. == Writings ==