Ah! poor religion, thou hast been sorely shot at by cruel foes, but thou hast not been wounded one-half so dangerously by thy foes as by thy friends. Who made those wounds in the fair hand of Godliness? The professor who used the dagger of hypocrisy. The man who with pretences, enters the fold, being nought but a wolf in sheep’s clothing, worries the flock more than the lion outside. There is no weapon half so deadly as a Judas-kiss. Inconsistent professors injure the gospel more than the sneering critic or the infidel.
—Charles Haddon Spurgeon, Morning and Evening (17 May, Morning)
["Professor" in this context simply means "one who professes."]