Sentence:  When we see the steady and methodical inculcation into humanity of the <WSD>idea</WSD> of man 's worthlessness - until redeemed - the necessity of the Devil may become evident as a weapon , a weapon designed and used time and time again in every age to whip men into a surrender to a particular church or church-state '' . 
Meaning of the word marked with <WSD> tags:  the content of cognition; the main thing you are thinking about