God also allows Satan to trounce some of his saints by temptation in order to train them to help fellow-brethren in like conditions. He allows them to train under Satan’s lash, to get experience in the ways of Satan’s and of their own hearts. All the plots of hell have not so much as shaken God’s hand to spoil one letter or line he has been drawing. The mysteriousness of his providence hangs a curtain over this work that we cannot see what he is doing.
William Gurnall, The Christian in Complete Armor, I:100-101