In my opinion there is a large error being made my some atheists when they discuss Communism and any role atheism may have played in their actions against Christianity and other religions. One of the most notable that come to mind is Hector Avalos.
In his book Fighting Words: The Origins Of Religious Violence Avalos argues that, while political motivations were more of a factor, atheism did have a role in the actions of the Communists. Avalos writes,
Our discussion will show that Stalin’s reign of terror has as much to do with politics as it did with atheism. (325)
Despite this strong stance, Avalos later admits that,
[W]e cannot find any direct evidence that Stalin’s own personal agenda killed because of atheism [...] [h]owever, we also said that inference was also an allowable method to establish causation, and we can do the same with Stalin. Stalin did follow many antireligious policies that can reasonably be attributed to his atheism. (326)
This popular atheist is guilty of committing one of the same errors Christian apologists make when discussing this issue: the belief that anti-religious actions are inherently “atheistic” in some way.
As Avalos just admitted, there is no direct evidence that Stalin (and from my research, no other Communist) killed because he was an atheist. With atheism being a motivating factor out of the equation what else could be the cause? The Marxist Communist ideology. It is illogical to assume someone’s motivations by just looking at their actions while not taking into account how important another factor might be. This is especially true when we look at the writings of the Communists and study the ideology they supported and tried to implement, which gives us a very good insight into what the most reasonable motivating factor was: their belief that certain institutions hindered the socialist progress of man and one of those was religion.
Vladimir Lenin wrote,
The combating of religion cannot be confined to abstract ideological preaching...It must be linked up with the concrete practice of the class movement, which aims at eliminating the social roots of religion...It means that Social Democracy's atheist propaganda must be subordinated to its basic task - the development of the class struggle of the exploited masses against the exploiters. [emphasis in original] 
Lenin also wrote,
The deepest root of religion in the socially downtrodden condition of the working masses and their apparently complete helplessness in the face of the blind forces of capitalism, which every day and every hour inflicts upon ordinary working people the most horrible suffering and the most savage torment, a thousand times more severe than those inflicted by extraordinary events, such as wars [and] earthquakes. [emphasis mine]
- V.I. Lenin, The Attitude of the Worker's Party to Religion
Here are two more examples:
Religion is by no means the result of exceptional ignorance and darkness, just as it is not a question of simple logic, the result of false thinking. It has its roots in the social life, in the conditions of existence; it grows upon the soil of definite social relations and is determined by the class position in society of the one or the other group. - Communist Party Conference on Antireligious Propaganda, Article IX, April 1926 
Here is another one:
To the query, “Does modern civilization need religion?” the Communist answer is “yes,” so far as decaying capitalist civilization is concerned. There, under the pressure of crisis, in an atmosphere of uncertainty and fear, religion serves as an escape mechanism for the classes which history has already condemned. - Julius Hecker, 1933 
It was believed that religious belief was a necessary aspect of pre-socialist life but was not needed after the society transformed into a socialist one. The Communists’ attempts to create such a socialist society resulted in Stalin’s “Great Terror” and other atrocities since the population did not want to work on collective farms, and the Communists’ attempts to do away with all things they believed would hinder or be unnecessary in a socialist society, which included religion.
One thing you must ask yourself as you read through the above quotes: Do any of these mention atheism as the cause of their dislike of religion? No. It was their Communist ideology which caused them to believe that religion was a hindrance to their socialist utopia and therefore it had to go.
When I read the excellent book by Paul Gabel called And God Created Lenin: Marxism vs Religion In Russia, 1917-1929 he recounts many of the acts of persecution of religion and the murder of Christians that occurred in Russia by the Communists, and I can understand how reading these stories makes one wonder if perhaps atheism was an influence, though something Gabel does in his book that I haven’t seen in any other history book about Communism is explain Marxist ideology and how it relates to religion. This places the Communists’ actions, in a sense, in their historical and ideological contexts, rather than just telling story after story about how atheists murdered all of these religious people, which is exactly how the Christians like to frame the debate. However, to understand why the Communists did what they did you have to also understand their beliefs and then it becomes clear.
Because it’s never been demonstrated that atheism was a factor and all of the evidence points to the Communists’ ideology it’s my opinion that atheism was not a factor in motivating the Communists, and the Marxist doctrines look to be the sole cause.
Throughout the many books and websites dealing with this subject of atheism and Communism that I’ve read I don’t recall finding anyone making use of this very important and relevant information about the Communists’ ideology. With this post I hope that all atheists who wish to partake in this debate will take a little time to learn about the ideology of Marxism and Communism and this will hopefully raise the level of the debate on the issue because the subject of ideology seems mostly absent from this discussion, and I feel this argument is the best defense against this very common charge by Christian apologists.
In conclusion, I believe the error some atheists (and especially Christians) make when discussing this issue is they focus solely on the historical events of Communist Russia (the religious persecution, murder of clergy, and church closures) and not on the Communists’ ideological beliefs and how they were motivated by them. If one paid more attention to the latter subject I believe less people would be taken in by this Christian propaganda.
1. And God Created Lenin: Marxism vs. Religion in Russia, 1917-1929, by Paul Gabel, Prometheus Books, 2005; 90
2. Ibid.; 75
3. Ibid.; 75