Communist Bukharin's Easter Greeting

I used this powerful illustration on Easter 2001.  I am sure that many others have used it on Easter too - a simple Google of Bukharin's name amply confirms this.  But is it true?  TruthorFiction.com calls the story "unproven" and says, "This story has been told through the years as having happened in various settings, usually Russia. Some versions have it happen in the 1930's. Others put it in the 1920's. There are several different names ascribed to the communist leader who was speaking to the crowd. We have not found a historically reliable source for the story. Can anyone help us out?"  <http://www.truthorfiction.com/rumors/h/heisrisen.htm>

Here is a popular version of the illustration from Rev. Brett Blair's Illustrations by Email, www.sermonillustrations.com, in 2001:

You probably do not remember the name Nikolai Ivanovich Bukharin nor should you. But during his day he was as powerful a man as there was on earth. A Russian Communist leader, he took part in the Bolshevik Revolution 1917, was editor of the Soviet newspaper Pravda (which by the way means truth), and was a full member of the Politburo. His works on economics and political science are still read today. There is a story told about a journey he took from Moscow to Kiev in 1930 to address a huge assembly on the subject of atheism. Addressing the crowd he aimed his heavy artillery at Christianity, hurling insult, argument, and proof against it.

An hour later he was finished. He looked out at what seemed to be the smoldering ashes of men’s faith. "Are there any questions?" Bukharin demanded. Deafening silence filled the auditorium but then one man approached the platform and mounted the lectern standing near the communist leader. He surveyed the crowd first to the left then to the right. Finally he shouted the ancient greeting known well in the Russian Orthodox Church: "CHRIST IS RISEN!"

En masse the crowd arose as one man and the response came crashing like the sound of thunder: "HE IS RISEN INDEED!"