@ Jack ''I would take the position that the Khmer Rouge were as much True Believers as any theist.''
I thoroughly agree militant atheism is of itself a belief system. Often substituting a belief in the all encompassing explanatory power of the theory of natural selection or, as I prefer to call it, the religion of evolutionism.
As to atheism amongst communists the apple never falls far from the tree. This from Stalin himself in preparation for the implementation of the Great Turn:
"What has happened is to a certain extent the same manoeuvre (with corresponding reservations, of course) as took place in 1921, when, in view of the famine in the country, the Party led by Lenin raised the question of removing valuables from churches for the purpose of acquiring grain for the famine-stricken regions, basing a large-scale anti-religious campaign on tins, and when the priests, hanging on to the valuables, spoke out against the starving masses and thereby aroused the anger of the masses against the church in general, against religious superstition, in particular, and especially against priests and their leader. There were some cranks in our party then who thought that Lenin only began to understand the need for a struggle against the church in 1921 (laughter), and not before then. This is ridiculous, of course, comrades. Of course, Lenin understood the need for a struggle against the church before 1921 as well. But this is not the point. The point is to link a broad, large-scale anti-religious campaign with the vital interests of the masses, so that it, this campaign, is supported by the masses".
J.Stalin. 0 rabotakh aprel'skogo ob'edinennogo plenuma TsK i TsKK. Gosizdat. 1928, pp. 28-30.
In my view militant atheism has at least as much blood on its hands as religious fundamentalism, partuicularly in the context of the last century, perhaps the most barbaric period in human history.