I think that one of the things I object to in such pieces when discussing HPL is that they present a monolithic view on his part, which is far from the truth. His view on such matters was quite complex and not at all easily summed up. One might argue, of course, that such articles rely on the fiction for the impressions they receive, yet here we also have quotations from letters and essays; the same letters and essays which, when read attentively, show just how complex and difficult to summarize his positions on these things were.
Much has been made (largely rightly) of Lovecraft's atheistic position; yet he well understood the need of human beings for myths, and in fact sympathized with those who found in tradition and myth beauty and a source of emotional sustenance. At times he even had kind things to say about this or that aspect of religion. But he did not believe -- based, as one of the excerpts presented makes clear, on the best evidence available -- in the objective, factual truth of any religious view... and so far the evidence has tended to back his view much more than that of Lewis. And, as Lovecraft was quite aware, one of the reasons religion continues to exist is that it does indeed fulfill, at least to some degree, an emotional "need" or desire for many, regardless of the factual basis or lack of same of whatever religion may be involved. Lovecraft was also quite aware that all the world's major religions tend, in the end, to have as much validity when it comes to the supernatural aspects of their beliefs as each other, yet they obviously can't all be right. Nor, given the fact that human beings have existed such a short time, is it at all likely that we have any special importance in the "scheme of things"... as he famously commented in another context, no more than mosquitoes, rats, lice, etc., or "any other form of biological energy". To assign to us any more significance than any other form of life (or energy, for that matter) on a cosmic scale, is simply unwarrantable if one relies on evidence rather than the desire to have it so.
Which is not to say that he did not realize just how genuinely poignant a pang the loss of such belief would engender for many, nor how tragic the outcome might be; simply that he recognized that this matters (so far as we have any genuine evidence) only to us (and, perhaps, insofar as they have the cognitive ability to evolve such thoughts, to those species which are dependent on or in close relationship -- friendly or otherwise -- with us). Yet to us, as he also rightly noted, such things are supremely important, and to therefore be taken into consideration when dealing with human psychology and relationships.
I won't go into Lewis because I frankly don't know that much about him other than the Narnia books, the Ransom trilogy, and some of his apologetics, none of which I have read for some time. I would, however, venture to guess that Lewis' views, too, were more complex than is often credited. I simply feel that, if one is going to undertake such a comparison, one had better do a much more thorough job of research than I see here; else it comes across less as a balanced comparison than having an axe to grind in order to build up a favored writer at the expense of another. And, in this case, that "other" happens to be a writer whose thoughts on such issues are intensely difficult to summarize without doing them an injustice.