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The calendar repeats so any one day in the calendar year will also repeat.  Human history, on the other hand, does not repeat so any one event in human history is singular. To speak of ""the most significant and Holy event in human history"" is to speak of a single event.  If Rawat had said ""the most significant and Holy event of the year"" you'd be right.  But he didn't and you're not.  Plain as day. 
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