A beautiful thread. Sensitive, considered and worthy of your time.
First of all, literature can be secular while being fundamentally religious. Besides, all modern books of the Western Canon (and I mean modern in opposition to ancient) are culturally Christian. Our secular literature - whether religious or not - is largely rooted in highly moral works such as Dante's, Aquinas's, Augustine's, etc.
Secondly, the point is that these dictators (and tyrants in general) were not concerned with truth - not outwardly. Plato talks about this, Orwell, Solzhenitzyn, and so many others. The Gulag Archipelago is one of the books that best presents the problem, and in fact it mentions, with the example of the Inquisitoon, how religion itself can be manipulated to serve evil ends.
Appreciating art, as I always say, is an act of transcendence, it is a search for some deeper, immutable truth - some essence beyond the material plane of things. It is fundamentally a spiritual act, whether the work is secular or not. And of course spirituality comes from religion (which in primitive times was pretty much the same as culture), which means our emotions while reading a great book are essentially religious emotions - and this does not contradict one's agnosticism or disbelief in God. But as a Christian I can say that, yes, many of the great works of the Canon, including so many written by non-believers, are absolutely vital to my faith and daily life as a believer.
I understand, Jaycel seems to have a problem with the word 'Godless' - it's certainly not the best word in all cases. I also understand that the magazine may have had solely moralistic purposes in mind (I have no idea, as I can only read a few paragraphs). But nonetheless one thing is clear: those dictators were objectively evil, and they certainly were not concerned with the transcendental purposes of great art (especially the communists), at least not outwardly, which resulted (especially in communist countries) in corrupted governments and materialistic societies, because truth was manipulated. Therefore, it does not matter to this discussion how wide their reading may have been (they were without a doubt profoundly intelligent leaders), or how deeply they enjoyed it, since they turned it all towards 'larger,' false, and corrupted ends.
To take a very fascinating example: James Joyce. He was either an agnostic or an atheist who rebelled radically against Catholicism and Ireland (in a very blasphemous way at times), yet at the same time he had a profound love for both. Is that contradictory? Somehow, not in the slightest. And what contradiction there is in it becomes irrelevant in the transcendental act of appreciating his work and personality. (You must read him to understand this.) Ergo, he was deeply Christian in a cultural sense, and in fact two of his favourite authors were Dante and Aquinas, whom he fervently defended every chance he got. He even attended mass sometimes for the aesthetic pleasure it gave him! And what is this thirst for aesthetic pleasure if not a thirst for truth, whatever way you see it? As Keats says, 'Beauty is truth, truth beauty.' And not only this, but Joyce always firmly believed in the soul. 'In Joyce's work the soul—a word which he never renounced—carries off the victory.' (Ellmann)
And it is the soul that must carry off the victory - in daily life as well. Not violence, not manipulating the truth, not oppression, not a political agenda, not depravity - but the individual soul in its confrontation with mortality and in its search of a deeper reality.