I am not doubting, but I have not ever read an authoritative account of this. It is one of those things we all assume is true when we hear it, but is it?
destro, you can, unfortunately, take that statement to the bank.
The KGB ran the Russian, and other COMBLOC Orthodox Churches. They used the church to infiltrate agents into orthodox monasteries and church posts in, among other places, the Middle East and of course, to keep tabs on churchgoers.
The miracle is that the churches were not totally compromised, that is many bishops and priests were in effect, "double agents,"who were trying to preserve their faith and traditions somehow. Nowadays, figuring out who's who is the problem.
In China, there is, even now, an entire Roman Catholic Church run by the CHICOM state. There is also an underground church directed from Rome, which is persecuted severely.
Nor were the Communist efforts to undermine and subvert religion directed solely at the Catholic Churches, including the Orthodox. They did a damn good job of running the World Council of Churches, and infiltrated the Lutheran Church of East Germany very thoroughly. Pretty damn confusing.