Christians who upstaged their atheist Russian leader-Unproven!

The Christians Who Upstaged Their Atheist Russian  LeaderUnproven!

Summary of eRumor:
This story talks about Ivanovich Bukharin, a powerful Russian leader in the early part of the 20th century.  In 1930, he is said to have traveled to Kiev to deliver an address to a large crowd on the subject of atheism.  After a an hour of delivering his best arguments against faith, he asked if there were any questions.  One man came from the crowd to the front and loudly proclaimed the ancient Orthodox greeting “Christ is risen!”  Then the crowd responded with the ancient Orthodox response “He is risen indeed!”
The Truth:
This story has been told through the years as having happened in various settings, usually Russia.  Some versions it happened 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?