Mr Gorbachev's surprise visit confirmed decades of rumours that, although he was forced to publicly pronounce himself an atheist, he was in fact a Christian, and casts a meeting with Pope John Paul II in 1989 in a new light.
Ronald Reagan, the former United States president, allegedly told his close aides on a number of occasions that he felt his opponent during the Cold War was a "closet believer".
Mr Reagan held deep religious convictions himself. However, until now Mr Gorbachev has allowed himself to express only pantheistic views, saying in one interview "nature is my god".
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-Is there such a thing as a "Closet Christian"?
-Does this fall into the "If you deny me before man, I will deny you before the Father" category?
-Do you think Mikhail Gorbachev's claim to be a Christian had influence as to how he approached the cold war and the subsequent break up of the Soviet Union?