This is quite possibly one of the best sources published in the English language for anyone who wishes to understand the 70 year continuous campaign in the Soviet Union to wipe out religion and replace it with atheism. Dr. Pospielovsky had spent most of his career studying the Orthodox church underneath Soviet rule, and his lifetime experiencing and collection of information is reproduced in these volumes for laypeople to understand.
I was shocked to discover some of the things he unearthed, including the putting of religious believers into psychiatric hospitals in order to 'cure' them of their faith, or the excessive taxation schemes that were placed on Orthodox clergy during the 1930s that required them to sometimes pay more than 100% of their income (and failure to do so could lead to arrest or even execution). In some ways these volumes are a kind of modern-day martyrology, although they are presented using critical analysis under an academic lens.
He presents both sides, and uses original sources gathered from both the communist state and the religious believers. He shows both how the church reacted to its persecution, and how the atheistic state understood as well as re-interpreted its role over the years.
It should be noted, however, that these volumes deal largely with the Orthodox church (to which denomination Dr. Pospielovsky belonged); other faiths, while also given significant treatment, tend to be less thoroughly analyzed. There is not much analysis of Islam, even though it was a major religion in the USSR.
They are very few other academics who have treated this subject with the kind of depth that is presented here, and these volumes would serve well as a required reading for university curricula that concerned either the issues of Soviet dealing with religion or state atheism.